diff --git a/modules/openapi-generator/src/main/resources/python/api.mustache b/modules/openapi-generator/src/main/resources/python/api.mustache
index 913e0dbbb28..70f316a2e7f 100644
--- a/modules/openapi-generator/src/main/resources/python/api.mustache
+++ b/modules/openapi-generator/src/main/resources/python/api.mustache
@@ -23,14 +23,14 @@ from {{packageName}}.exceptions import (  # noqa: F401
 
 
 {{#operations}}
-class {{classname}}(object):
+class {{classname}}:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -65,10 +65,10 @@ class {{classname}}(object):
 {{/allParams}}
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -76,7 +76,8 @@ class {{classname}}(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the {{operationId}}_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the {{operationId}}_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
 {{#asyncio}}
         if async_req is not None:
             kwargs['async_req'] = async_req
@@ -103,7 +104,7 @@ class {{classname}}(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/modules/openapi-generator/src/main/resources/python/api_client.mustache b/modules/openapi-generator/src/main/resources/python/api_client.mustache
index 1c204ad1595..1a94f56c97b 100644
--- a/modules/openapi-generator/src/main/resources/python/api_client.mustache
+++ b/modules/openapi-generator/src/main/resources/python/api_client.mustache
@@ -24,7 +24,7 @@ from {{packageName}} import rest
 from {{packageName}}.exceptions import ApiValueError, ApiException
 
 
-class ApiClient(object):
+class ApiClient:
     """Generic API client for OpenAPI client library builds.
 
     OpenAPI generic API client. This client handles the client-
@@ -56,7 +56,7 @@ class ApiClient(object):
     _pool = None
 
     def __init__(self, configuration=None, header_name=None, header_value=None,
-                 cookie=None, pool_threads=1):
+                 cookie=None, pool_threads=1) -> None:
         # use default configuration if none is provided
         if configuration is None:
             configuration = Configuration.get_default()
@@ -348,7 +348,7 @@ class ApiClient(object):
         if data is None:
             return None
 
-        if type(klass) == str:
+        if isinstance(klass, str):
             if klass.startswith('List['):
                 sub_kls = re.match(r'List\[(.*)]', klass).group(1)
                 return [self.__deserialize(sub_data, sub_kls)
diff --git a/modules/openapi-generator/src/main/resources/python/api_response.mustache b/modules/openapi-generator/src/main/resources/python/api_response.mustache
index d81c2ff5847..a0b62b95246 100644
--- a/modules/openapi-generator/src/main/resources/python/api_response.mustache
+++ b/modules/openapi-generator/src/main/resources/python/api_response.mustache
@@ -18,7 +18,7 @@ class ApiResponse:
                  status_code=None,
                  headers=None,
                  data=None,
-                 raw_data=None):
+                 raw_data=None) -> None:
         self.status_code = status_code
         self.headers = headers
         self.data = data
diff --git a/modules/openapi-generator/src/main/resources/python/api_test.mustache b/modules/openapi-generator/src/main/resources/python/api_test.mustache
index c3bbe4b822f..ad2b8a63fe1 100644
--- a/modules/openapi-generator/src/main/resources/python/api_test.mustache
+++ b/modules/openapi-generator/src/main/resources/python/api_test.mustache
@@ -4,22 +4,20 @@
 
 import unittest
 
-import {{packageName}}
 from {{apiPackage}}.{{classFilename}} import {{classname}}  # noqa: E501
-from {{packageName}}.rest import ApiException
 
 
 class {{#operations}}Test{{classname}}(unittest.TestCase):
     """{{classname}} unit test stubs"""
 
-    def setUp(self):
-        self.api = {{apiPackage}}.{{classFilename}}.{{classname}}()  # noqa: E501
+    def setUp(self) -> None:
+        self.api = {{classname}}()  # noqa: E501
 
-    def tearDown(self):
+    def tearDown(self) -> None:
         pass
 
    {{#operation}}
-    def test_{{operationId}}(self):
+    def test_{{operationId}}(self) -> None:
         """Test case for {{{operationId}}}
 
 {{#summary}}
diff --git a/modules/openapi-generator/src/main/resources/python/asyncio/rest.mustache b/modules/openapi-generator/src/main/resources/python/asyncio/rest.mustache
index 98c811e513e..c97788d0c5c 100644
--- a/modules/openapi-generator/src/main/resources/python/asyncio/rest.mustache
+++ b/modules/openapi-generator/src/main/resources/python/asyncio/rest.mustache
@@ -18,7 +18,7 @@ logger = logging.getLogger(__name__)
 
 class RESTResponse(io.IOBase):
 
-    def __init__(self, resp, data):
+    def __init__(self, resp, data) -> None:
         self.aiohttp_response = resp
         self.status = resp.status
         self.reason = resp.reason
@@ -33,9 +33,9 @@ class RESTResponse(io.IOBase):
         return self.aiohttp_response.headers.get(name, default)
 
 
-class RESTClientObject(object):
+class RESTClientObject:
 
-    def __init__(self, configuration, pools_size=4, maxsize=None):
+    def __init__(self, configuration, pools_size=4, maxsize=None) -> None:
 
         # maxsize is number of requests to host that are allowed in parallel
         if maxsize is None:
diff --git a/modules/openapi-generator/src/main/resources/python/configuration.mustache b/modules/openapi-generator/src/main/resources/python/configuration.mustache
index ac51800bab8..c3799c0c5e0 100644
--- a/modules/openapi-generator/src/main/resources/python/configuration.mustache
+++ b/modules/openapi-generator/src/main/resources/python/configuration.mustache
@@ -11,7 +11,6 @@ import sys
 import urllib3
 
 import http.client as httplib
-from {{packageName}}.exceptions import ApiValueError
 
 JSON_SCHEMA_VALIDATION_KEYWORDS = {
     'multipleOf', 'maximum', 'exclusiveMaximum',
@@ -19,7 +18,7 @@ JSON_SCHEMA_VALIDATION_KEYWORDS = {
     'minLength', 'pattern', 'maxItems', 'minItems'
 }
 
-class Configuration(object):
+class Configuration:
     """This class contains various settings of the API client.
 
     :param host: Base url.
@@ -45,7 +44,8 @@ class Configuration(object):
       configuration.
     :param server_operation_variables: Mapping from operation ID to a mapping with
       string values to replace variables in templated server configuration.
-      The validation of enums is performed for variables with defined enum values before.
+      The validation of enums is performed for variables with defined enum
+      values before.
     :param ssl_ca_cert: str - the path to a file of concatenated CA certificates
       in PEM format.
 
@@ -146,7 +146,7 @@ conf = {{{packageName}}}.Configuration(
                  server_index=None, server_variables=None,
                  server_operation_index=None, server_operation_variables=None,
                  ssl_ca_cert=None,
-                 ):
+                 ) -> None:
         """Constructor
         """
         self._base_path = "{{{basePath}}}" if host is None else host
diff --git a/modules/openapi-generator/src/main/resources/python/exceptions.mustache b/modules/openapi-generator/src/main/resources/python/exceptions.mustache
index baee9004b1e..8a155a9fe08 100644
--- a/modules/openapi-generator/src/main/resources/python/exceptions.mustache
+++ b/modules/openapi-generator/src/main/resources/python/exceptions.mustache
@@ -8,7 +8,7 @@ class OpenApiException(Exception):
 
 class ApiTypeError(OpenApiException, TypeError):
     def __init__(self, msg, path_to_item=None, valid_classes=None,
-                 key_type=None):
+                 key_type=None) -> None:
         """ Raises an exception for TypeErrors
 
         Args:
@@ -36,7 +36,7 @@ class ApiTypeError(OpenApiException, TypeError):
 
 
 class ApiValueError(OpenApiException, ValueError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Args:
             msg (str): the exception message
@@ -54,7 +54,7 @@ class ApiValueError(OpenApiException, ValueError):
 
 
 class ApiAttributeError(OpenApiException, AttributeError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Raised when an attribute reference or assignment fails.
 
@@ -73,7 +73,7 @@ class ApiAttributeError(OpenApiException, AttributeError):
 
 
 class ApiKeyError(OpenApiException, KeyError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Args:
             msg (str): the exception message
@@ -91,7 +91,7 @@ class ApiKeyError(OpenApiException, KeyError):
 
 class ApiException(OpenApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         if http_resp:
             self.status = http_resp.status
             self.reason = http_resp.reason
@@ -118,30 +118,30 @@ class ApiException(OpenApiException):
 
 class BadRequestException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(BadRequestException, self).__init__(status, reason, http_resp)
 
 class NotFoundException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(NotFoundException, self).__init__(status, reason, http_resp)
 
 
 class UnauthorizedException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(UnauthorizedException, self).__init__(status, reason, http_resp)
 
 
 class ForbiddenException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(ForbiddenException, self).__init__(status, reason, http_resp)
 
 
 class ServiceException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(ServiceException, self).__init__(status, reason, http_resp)
 
 
diff --git a/modules/openapi-generator/src/main/resources/python/model_anyof.mustache b/modules/openapi-generator/src/main/resources/python/model_anyof.mustache
index 74a007fbc19..adec7c41868 100644
--- a/modules/openapi-generator/src/main/resources/python/model_anyof.mustache
+++ b/modules/openapi-generator/src/main/resources/python/model_anyof.mustache
@@ -40,7 +40,7 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
     }
 {{/discriminator}}
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
@@ -177,4 +177,4 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
 {{{.}}}
 {{/vendorExtensions.x-py-postponed-model-imports}}
 {{classname}}.update_forward_refs()
-{{/vendorExtensions.x-py-postponed-model-imports.size}}
\ No newline at end of file
+{{/vendorExtensions.x-py-postponed-model-imports.size}}
diff --git a/modules/openapi-generator/src/main/resources/python/model_oneof.mustache b/modules/openapi-generator/src/main/resources/python/model_oneof.mustache
index c7afad4d172..2f23bade341 100644
--- a/modules/openapi-generator/src/main/resources/python/model_oneof.mustache
+++ b/modules/openapi-generator/src/main/resources/python/model_oneof.mustache
@@ -39,7 +39,7 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
     }
 {{/discriminator}}
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
@@ -203,4 +203,4 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
 {{{.}}}
 {{/vendorExtensions.x-py-postponed-model-imports}}
 {{classname}}.update_forward_refs()
-{{/vendorExtensions.x-py-postponed-model-imports.size}}
\ No newline at end of file
+{{/vendorExtensions.x-py-postponed-model-imports.size}}
diff --git a/modules/openapi-generator/src/main/resources/python/model_test.mustache b/modules/openapi-generator/src/main/resources/python/model_test.mustache
index 93ebf99b14f..2c7fa1f132c 100644
--- a/modules/openapi-generator/src/main/resources/python/model_test.mustache
+++ b/modules/openapi-generator/src/main/resources/python/model_test.mustache
@@ -7,9 +7,7 @@ import datetime
 
 {{#models}}
 {{#model}}
-import {{packageName}}
 from {{modelPackage}}.{{classFilename}} import {{classname}}  # noqa: E501
-from {{packageName}}.rest import ApiException
 
 class Test{{classname}}(unittest.TestCase):
     """{{classname}} unit test stubs"""
@@ -21,21 +19,21 @@ class Test{{classname}}(unittest.TestCase):
         pass
 {{^isEnum}}
 
-    def make_instance(self, include_optional):
+    def make_instance(self, include_optional) -> {{classname}}:
         """Test {{classname}}
             include_option is a boolean, when False only required
             params are included, when True both required and
             optional params are included """
         # uncomment below to create an instance of `{{{classname}}}`
         """
-        model = {{packageName}}.models.{{classFilename}}.{{classname}}()  # noqa: E501
-        if include_optional :
+        model = {{classname}}()  # noqa: E501
+        if include_optional:
             return {{classname}}(
                 {{#vars}}
-                {{name}} = {{{example}}}{{^example}}None{{/example}}{{^-last}}, {{/-last}}
+                {{name}} = {{{example}}}{{^example}}None{{/example}}{{^-last}},{{/-last}}
                 {{/vars}}
             )
-        else :
+        else:
             return {{classname}}(
                 {{#vars}}
                 {{#required}}
diff --git a/modules/openapi-generator/src/main/resources/python/rest.mustache b/modules/openapi-generator/src/main/resources/python/rest.mustache
index c8748d7a6ef..f49dee2bed4 100644
--- a/modules/openapi-generator/src/main/resources/python/rest.mustache
+++ b/modules/openapi-generator/src/main/resources/python/rest.mustache
@@ -19,7 +19,7 @@ logger = logging.getLogger(__name__)
 
 class RESTResponse(io.IOBase):
 
-    def __init__(self, resp):
+    def __init__(self, resp) -> None:
         self.urllib3_response = resp
         self.status = resp.status
         self.reason = resp.reason
@@ -34,9 +34,9 @@ class RESTResponse(io.IOBase):
         return self.urllib3_response.headers.get(name, default)
 
 
-class RESTClientObject(object):
+class RESTClientObject:
 
-    def __init__(self, configuration, pools_size=4, maxsize=None):
+    def __init__(self, configuration, pools_size=4, maxsize=None) -> None:
         # urllib3.PoolManager will pass all kw parameters to connectionpool
         # https://github.com/shazow/urllib3/blob/f9409436f83aeb79fbaf090181cd81b784f1b8ce/urllib3/poolmanager.py#L75  # noqa: E501
         # https://github.com/shazow/urllib3/blob/f9409436f83aeb79fbaf090181cd81b784f1b8ce/urllib3/connectionpool.py#L680  # noqa: E501
diff --git a/modules/openapi-generator/src/main/resources/python/signing.mustache b/modules/openapi-generator/src/main/resources/python/signing.mustache
index 8dca7e2d1ff..bb2850fdcc0 100644
--- a/modules/openapi-generator/src/main/resources/python/signing.mustache
+++ b/modules/openapi-generator/src/main/resources/python/signing.mustache
@@ -56,7 +56,7 @@ HASH_SHA256 = 'sha256'
 HASH_SHA512 = 'sha512'
 
 
-class HttpSigningConfiguration(object):
+class HttpSigningConfiguration:
     """The configuration parameters for the HTTP signature security scheme.
     The HTTP signature security scheme is used to sign HTTP requests with a private key
     which is in possession of the API client.
@@ -112,7 +112,7 @@ class HttpSigningConfiguration(object):
                  signed_headers=None,
                  signing_algorithm=None,
                  hash_algorithm=None,
-                 signature_max_validity=None):
+                 signature_max_validity=None) -> None:
         self.key_id = key_id
         if signing_scheme not in {SCHEME_HS2019, SCHEME_RSA_SHA256, SCHEME_RSA_SHA512}:
             raise Exception("Unsupported security scheme: {0}".format(signing_scheme))
diff --git a/modules/openapi-generator/src/main/resources/python/tornado/rest.mustache b/modules/openapi-generator/src/main/resources/python/tornado/rest.mustache
index 59f14ffab1e..6b91cdef986 100644
--- a/modules/openapi-generator/src/main/resources/python/tornado/rest.mustache
+++ b/modules/openapi-generator/src/main/resources/python/tornado/rest.mustache
@@ -20,7 +20,7 @@ logger = logging.getLogger(__name__)
 
 class RESTResponse(io.IOBase):
 
-    def __init__(self, resp):
+    def __init__(self, resp) -> None:
         self.tornado_response = resp
         self.status = resp.code
         self.reason = resp.reason
@@ -39,9 +39,9 @@ class RESTResponse(io.IOBase):
         return self.tornado_response.headers.get(name, default)
 
 
-class RESTClientObject(object):
+class RESTClientObject:
 
-    def __init__(self, configuration, pools_size=4, maxsize=4):
+    def __init__(self, configuration, pools_size=4, maxsize=4) -> None:
         # maxsize is number of requests to host that are allowed in parallel
 
         self.ca_certs = configuration.ssl_ca_cert
diff --git a/samples/client/echo_api/python/openapi_client/api/body_api.py b/samples/client/echo_api/python/openapi_client/api/body_api.py
index fa1953cecd3..196e2a6389f 100644
--- a/samples/client/echo_api/python/openapi_client/api/body_api.py
+++ b/samples/client/echo_api/python/openapi_client/api/body_api.py
@@ -35,14 +35,14 @@ from openapi_client.exceptions import (  # noqa: F401
 )
 
 
-class BodyApi(object):
+class BodyApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -60,10 +60,10 @@ class BodyApi(object):
 
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -71,7 +71,8 @@ class BodyApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_binary_gif_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_binary_gif_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_binary_gif_with_http_info(**kwargs)  # noqa: E501
 
     @validate_arguments
@@ -88,7 +89,7 @@ class BodyApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -193,10 +194,10 @@ class BodyApi(object):
         :type body: bytearray
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -204,7 +205,8 @@ class BodyApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_body_application_octetstream_binary_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_body_application_octetstream_binary_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_body_application_octetstream_binary_with_http_info(body, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -223,7 +225,7 @@ class BodyApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -344,10 +346,10 @@ class BodyApi(object):
         :type files: List[bytearray]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -355,7 +357,8 @@ class BodyApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_body_multipart_formdata_array_of_binary_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_body_multipart_formdata_array_of_binary_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_body_multipart_formdata_array_of_binary_with_http_info(files, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -374,7 +377,7 @@ class BodyApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -491,10 +494,10 @@ class BodyApi(object):
         :type body: object
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -502,7 +505,8 @@ class BodyApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_echo_body_free_form_object_response_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_echo_body_free_form_object_response_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_echo_body_free_form_object_response_string_with_http_info(body, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -521,7 +525,7 @@ class BodyApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -637,10 +641,10 @@ class BodyApi(object):
         :type pet: Pet
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -648,7 +652,8 @@ class BodyApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_echo_body_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_echo_body_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_echo_body_pet_with_http_info(pet, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -667,7 +672,7 @@ class BodyApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -783,10 +788,10 @@ class BodyApi(object):
         :type pet: Pet
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -794,7 +799,8 @@ class BodyApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_echo_body_pet_response_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_echo_body_pet_response_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_echo_body_pet_response_string_with_http_info(pet, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -813,7 +819,7 @@ class BodyApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -929,10 +935,10 @@ class BodyApi(object):
         :type tag: Tag
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -940,7 +946,8 @@ class BodyApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_echo_body_tag_response_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_echo_body_tag_response_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_echo_body_tag_response_string_with_http_info(tag, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -959,7 +966,7 @@ class BodyApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/client/echo_api/python/openapi_client/api/form_api.py b/samples/client/echo_api/python/openapi_client/api/form_api.py
index d0cc8730d4f..1137bfca321 100644
--- a/samples/client/echo_api/python/openapi_client/api/form_api.py
+++ b/samples/client/echo_api/python/openapi_client/api/form_api.py
@@ -33,14 +33,14 @@ from openapi_client.exceptions import (  # noqa: F401
 )
 
 
-class FormApi(object):
+class FormApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -64,10 +64,10 @@ class FormApi(object):
         :type string_form: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -75,7 +75,8 @@ class FormApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_form_integer_boolean_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_form_integer_boolean_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_form_integer_boolean_string_with_http_info(integer_form, boolean_form, string_form, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -98,7 +99,7 @@ class FormApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/client/echo_api/python/openapi_client/api/header_api.py b/samples/client/echo_api/python/openapi_client/api/header_api.py
index 4742d4c2174..a67fc13b277 100644
--- a/samples/client/echo_api/python/openapi_client/api/header_api.py
+++ b/samples/client/echo_api/python/openapi_client/api/header_api.py
@@ -33,14 +33,14 @@ from openapi_client.exceptions import (  # noqa: F401
 )
 
 
-class HeaderApi(object):
+class HeaderApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -64,10 +64,10 @@ class HeaderApi(object):
         :type string_header: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -75,7 +75,8 @@ class HeaderApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_header_integer_boolean_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_header_integer_boolean_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_header_integer_boolean_string_with_http_info(integer_header, boolean_header, string_header, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -98,7 +99,7 @@ class HeaderApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/client/echo_api/python/openapi_client/api/path_api.py b/samples/client/echo_api/python/openapi_client/api/path_api.py
index 12a2a5c8684..13203624883 100644
--- a/samples/client/echo_api/python/openapi_client/api/path_api.py
+++ b/samples/client/echo_api/python/openapi_client/api/path_api.py
@@ -31,14 +31,14 @@ from openapi_client.exceptions import (  # noqa: F401
 )
 
 
-class PathApi(object):
+class PathApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -60,10 +60,10 @@ class PathApi(object):
         :type path_integer: int
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -71,7 +71,8 @@ class PathApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the tests_path_string_path_string_integer_path_integer_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the tests_path_string_path_string_integer_path_integer_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.tests_path_string_path_string_integer_path_integer_with_http_info(path_string, path_integer, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -92,7 +93,7 @@ class PathApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/client/echo_api/python/openapi_client/api/query_api.py b/samples/client/echo_api/python/openapi_client/api/query_api.py
index 7d387c1adaf..59465cdc0cc 100644
--- a/samples/client/echo_api/python/openapi_client/api/query_api.py
+++ b/samples/client/echo_api/python/openapi_client/api/query_api.py
@@ -38,14 +38,14 @@ from openapi_client.exceptions import (  # noqa: F401
 )
 
 
-class QueryApi(object):
+class QueryApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -65,10 +65,10 @@ class QueryApi(object):
         :type enum_ref_string_query: StringEnumRef
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -76,7 +76,8 @@ class QueryApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_enum_ref_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_enum_ref_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_enum_ref_string_with_http_info(enum_ref_string_query, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -95,7 +96,7 @@ class QueryApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -208,10 +209,10 @@ class QueryApi(object):
         :type string_query: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -219,7 +220,8 @@ class QueryApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_query_datetime_date_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_query_datetime_date_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_query_datetime_date_string_with_http_info(datetime_query, date_query, string_query, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -242,7 +244,7 @@ class QueryApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -369,10 +371,10 @@ class QueryApi(object):
         :type string_query: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -380,7 +382,8 @@ class QueryApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_query_integer_boolean_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_query_integer_boolean_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_query_integer_boolean_string_with_http_info(integer_query, boolean_query, string_query, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -403,7 +406,7 @@ class QueryApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -520,10 +523,10 @@ class QueryApi(object):
         :type query_object: Pet
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -531,7 +534,8 @@ class QueryApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_query_style_deep_object_explode_true_object_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_query_style_deep_object_explode_true_object_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_query_style_deep_object_explode_true_object_with_http_info(query_object, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -550,7 +554,7 @@ class QueryApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -659,10 +663,10 @@ class QueryApi(object):
         :type query_object: TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -670,7 +674,8 @@ class QueryApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_query_style_deep_object_explode_true_object_all_of_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_query_style_deep_object_explode_true_object_all_of_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_query_style_deep_object_explode_true_object_all_of_with_http_info(query_object, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -689,7 +694,7 @@ class QueryApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -798,10 +803,10 @@ class QueryApi(object):
         :type query_object: TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -809,7 +814,8 @@ class QueryApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_query_style_form_explode_true_array_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_query_style_form_explode_true_array_string_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_query_style_form_explode_true_array_string_with_http_info(query_object, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -828,7 +834,7 @@ class QueryApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -937,10 +943,10 @@ class QueryApi(object):
         :type query_object: Pet
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -948,7 +954,8 @@ class QueryApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_query_style_form_explode_true_object_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_query_style_form_explode_true_object_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_query_style_form_explode_true_object_with_http_info(query_object, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -967,7 +974,7 @@ class QueryApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1076,10 +1083,10 @@ class QueryApi(object):
         :type query_object: DataQuery
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1087,7 +1094,8 @@ class QueryApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_query_style_form_explode_true_object_all_of_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_query_style_form_explode_true_object_all_of_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_query_style_form_explode_true_object_all_of_with_http_info(query_object, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -1106,7 +1114,7 @@ class QueryApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/client/echo_api/python/openapi_client/api_client.py b/samples/client/echo_api/python/openapi_client/api_client.py
index 3f407664d47..d9c39c44c8f 100644
--- a/samples/client/echo_api/python/openapi_client/api_client.py
+++ b/samples/client/echo_api/python/openapi_client/api_client.py
@@ -32,7 +32,7 @@ from openapi_client import rest
 from openapi_client.exceptions import ApiValueError, ApiException
 
 
-class ApiClient(object):
+class ApiClient:
     """Generic API client for OpenAPI client library builds.
 
     OpenAPI generic API client. This client handles the client-
@@ -64,7 +64,7 @@ class ApiClient(object):
     _pool = None
 
     def __init__(self, configuration=None, header_name=None, header_value=None,
-                 cookie=None, pool_threads=1):
+                 cookie=None, pool_threads=1) -> None:
         # use default configuration if none is provided
         if configuration is None:
             configuration = Configuration.get_default()
@@ -330,7 +330,7 @@ class ApiClient(object):
         if data is None:
             return None
 
-        if type(klass) == str:
+        if isinstance(klass, str):
             if klass.startswith('List['):
                 sub_kls = re.match(r'List\[(.*)]', klass).group(1)
                 return [self.__deserialize(sub_data, sub_kls)
diff --git a/samples/client/echo_api/python/openapi_client/api_response.py b/samples/client/echo_api/python/openapi_client/api_response.py
index d81c2ff5847..a0b62b95246 100644
--- a/samples/client/echo_api/python/openapi_client/api_response.py
+++ b/samples/client/echo_api/python/openapi_client/api_response.py
@@ -18,7 +18,7 @@ class ApiResponse:
                  status_code=None,
                  headers=None,
                  data=None,
-                 raw_data=None):
+                 raw_data=None) -> None:
         self.status_code = status_code
         self.headers = headers
         self.data = data
diff --git a/samples/client/echo_api/python/openapi_client/configuration.py b/samples/client/echo_api/python/openapi_client/configuration.py
index a9fcb250040..361ae879385 100644
--- a/samples/client/echo_api/python/openapi_client/configuration.py
+++ b/samples/client/echo_api/python/openapi_client/configuration.py
@@ -20,7 +20,6 @@ import sys
 import urllib3
 
 import http.client as httplib
-from openapi_client.exceptions import ApiValueError
 
 JSON_SCHEMA_VALIDATION_KEYWORDS = {
     'multipleOf', 'maximum', 'exclusiveMaximum',
@@ -28,7 +27,7 @@ JSON_SCHEMA_VALIDATION_KEYWORDS = {
     'minLength', 'pattern', 'maxItems', 'minItems'
 }
 
-class Configuration(object):
+class Configuration:
     """This class contains various settings of the API client.
 
     :param host: Base url.
@@ -50,7 +49,8 @@ class Configuration(object):
       configuration.
     :param server_operation_variables: Mapping from operation ID to a mapping with
       string values to replace variables in templated server configuration.
-      The validation of enums is performed for variables with defined enum values before.
+      The validation of enums is performed for variables with defined enum
+      values before.
     :param ssl_ca_cert: str - the path to a file of concatenated CA certificates
       in PEM format.
 
@@ -65,7 +65,7 @@ class Configuration(object):
                  server_index=None, server_variables=None,
                  server_operation_index=None, server_operation_variables=None,
                  ssl_ca_cert=None,
-                 ):
+                 ) -> None:
         """Constructor
         """
         self._base_path = "http://localhost:3000" if host is None else host
diff --git a/samples/client/echo_api/python/openapi_client/exceptions.py b/samples/client/echo_api/python/openapi_client/exceptions.py
index 50b1bc01826..ae3e985d2fe 100644
--- a/samples/client/echo_api/python/openapi_client/exceptions.py
+++ b/samples/client/echo_api/python/openapi_client/exceptions.py
@@ -19,7 +19,7 @@ class OpenApiException(Exception):
 
 class ApiTypeError(OpenApiException, TypeError):
     def __init__(self, msg, path_to_item=None, valid_classes=None,
-                 key_type=None):
+                 key_type=None) -> None:
         """ Raises an exception for TypeErrors
 
         Args:
@@ -47,7 +47,7 @@ class ApiTypeError(OpenApiException, TypeError):
 
 
 class ApiValueError(OpenApiException, ValueError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Args:
             msg (str): the exception message
@@ -65,7 +65,7 @@ class ApiValueError(OpenApiException, ValueError):
 
 
 class ApiAttributeError(OpenApiException, AttributeError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Raised when an attribute reference or assignment fails.
 
@@ -84,7 +84,7 @@ class ApiAttributeError(OpenApiException, AttributeError):
 
 
 class ApiKeyError(OpenApiException, KeyError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Args:
             msg (str): the exception message
@@ -102,7 +102,7 @@ class ApiKeyError(OpenApiException, KeyError):
 
 class ApiException(OpenApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         if http_resp:
             self.status = http_resp.status
             self.reason = http_resp.reason
@@ -129,30 +129,30 @@ class ApiException(OpenApiException):
 
 class BadRequestException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(BadRequestException, self).__init__(status, reason, http_resp)
 
 class NotFoundException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(NotFoundException, self).__init__(status, reason, http_resp)
 
 
 class UnauthorizedException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(UnauthorizedException, self).__init__(status, reason, http_resp)
 
 
 class ForbiddenException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(ForbiddenException, self).__init__(status, reason, http_resp)
 
 
 class ServiceException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(ServiceException, self).__init__(status, reason, http_resp)
 
 
diff --git a/samples/client/echo_api/python/openapi_client/rest.py b/samples/client/echo_api/python/openapi_client/rest.py
index c36d9d4647a..d05e077260d 100644
--- a/samples/client/echo_api/python/openapi_client/rest.py
+++ b/samples/client/echo_api/python/openapi_client/rest.py
@@ -30,7 +30,7 @@ logger = logging.getLogger(__name__)
 
 class RESTResponse(io.IOBase):
 
-    def __init__(self, resp):
+    def __init__(self, resp) -> None:
         self.urllib3_response = resp
         self.status = resp.status
         self.reason = resp.reason
@@ -45,9 +45,9 @@ class RESTResponse(io.IOBase):
         return self.urllib3_response.headers.get(name, default)
 
 
-class RESTClientObject(object):
+class RESTClientObject:
 
-    def __init__(self, configuration, pools_size=4, maxsize=None):
+    def __init__(self, configuration, pools_size=4, maxsize=None) -> None:
         # urllib3.PoolManager will pass all kw parameters to connectionpool
         # https://github.com/shazow/urllib3/blob/f9409436f83aeb79fbaf090181cd81b784f1b8ce/urllib3/poolmanager.py#L75  # noqa: E501
         # https://github.com/shazow/urllib3/blob/f9409436f83aeb79fbaf090181cd81b784f1b8ce/urllib3/connectionpool.py#L680  # noqa: E501
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/another_fake_api.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/another_fake_api.py
index 74d0a3c7de9..3ba5d212b86 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/another_fake_api.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/another_fake_api.py
@@ -32,14 +32,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class AnotherFakeApi(object):
+class AnotherFakeApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -67,10 +67,10 @@ class AnotherFakeApi(object):
         :type client: Client
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -78,7 +78,8 @@ class AnotherFakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the call_123_test_special_tags_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the call_123_test_special_tags_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.call_123_test_special_tags_with_http_info(client, **kwargs)  # noqa: E501
@@ -99,7 +100,7 @@ class AnotherFakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/default_api.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/default_api.py
index f9480b03abd..69cfa5ebedf 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/default_api.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/default_api.py
@@ -30,14 +30,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class DefaultApi(object):
+class DefaultApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -62,10 +62,10 @@ class DefaultApi(object):
 
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -73,7 +73,8 @@ class DefaultApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the foo_get_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the foo_get_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.foo_get_with_http_info(**kwargs)  # noqa: E501
@@ -91,7 +92,7 @@ class DefaultApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/fake_api.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/fake_api.py
index 1fa99033b98..292a52965c3 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/fake_api.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/fake_api.py
@@ -44,14 +44,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class FakeApi(object):
+class FakeApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -78,10 +78,10 @@ class FakeApi(object):
         :type body: object
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -89,7 +89,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_any_type_request_body_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_any_type_request_body_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.fake_any_type_request_body_with_http_info(body, **kwargs)  # noqa: E501
@@ -109,7 +110,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -226,10 +227,10 @@ class FakeApi(object):
         :type enum_ref: EnumClass
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -237,7 +238,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_enum_ref_query_parameter_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_enum_ref_query_parameter_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.fake_enum_ref_query_parameter_with_http_info(enum_ref, **kwargs)  # noqa: E501
@@ -257,7 +259,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -365,10 +367,10 @@ class FakeApi(object):
 
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -376,7 +378,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_health_get_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_health_get_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.fake_health_get_with_http_info(**kwargs)  # noqa: E501
@@ -394,7 +397,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -510,10 +513,10 @@ class FakeApi(object):
         :type header_1: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -521,7 +524,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_http_signature_test_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_http_signature_test_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.fake_http_signature_test_with_http_info(pet, query_1, header_1, **kwargs)  # noqa: E501
@@ -545,7 +549,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -671,10 +675,10 @@ class FakeApi(object):
         :type body: bool
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -682,7 +686,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_outer_boolean_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_outer_boolean_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.fake_outer_boolean_serialize_with_http_info(body, **kwargs)  # noqa: E501
@@ -703,7 +708,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -827,10 +832,10 @@ class FakeApi(object):
         :type outer_composite: OuterComposite
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -838,7 +843,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_outer_composite_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_outer_composite_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.fake_outer_composite_serialize_with_http_info(outer_composite, **kwargs)  # noqa: E501
@@ -859,7 +865,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -983,10 +989,10 @@ class FakeApi(object):
         :type body: float
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -994,7 +1000,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_outer_number_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_outer_number_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.fake_outer_number_serialize_with_http_info(body, **kwargs)  # noqa: E501
@@ -1015,7 +1022,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1139,10 +1146,10 @@ class FakeApi(object):
         :type body: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1150,7 +1157,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_outer_string_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_outer_string_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.fake_outer_string_serialize_with_http_info(body, **kwargs)  # noqa: E501
@@ -1171,7 +1179,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1295,10 +1303,10 @@ class FakeApi(object):
         :type outer_object_with_enum_property: OuterObjectWithEnumProperty
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1306,7 +1314,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_property_enum_integer_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_property_enum_integer_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.fake_property_enum_integer_serialize_with_http_info(outer_object_with_enum_property, **kwargs)  # noqa: E501
@@ -1327,7 +1336,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1448,10 +1457,10 @@ class FakeApi(object):
 
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1459,7 +1468,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_return_list_of_objects_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_return_list_of_objects_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.fake_return_list_of_objects_with_http_info(**kwargs)  # noqa: E501
@@ -1477,7 +1487,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1731,10 +1741,10 @@ class FakeApi(object):
         :type body: bytearray
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1742,7 +1752,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_body_with_binary_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_body_with_binary_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.test_body_with_binary_with_http_info(body, **kwargs)  # noqa: E501
@@ -1763,7 +1774,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1886,10 +1897,10 @@ class FakeApi(object):
         :type file_schema_test_class: FileSchemaTestClass
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1897,7 +1908,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_body_with_file_schema_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_body_with_file_schema_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.test_body_with_file_schema_with_http_info(file_schema_test_class, **kwargs)  # noqa: E501
@@ -1918,7 +1930,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2037,10 +2049,10 @@ class FakeApi(object):
         :type user: User
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2048,7 +2060,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_body_with_query_params_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_body_with_query_params_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.test_body_with_query_params_with_http_info(query, user, **kwargs)  # noqa: E501
@@ -2070,7 +2083,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2192,10 +2205,10 @@ class FakeApi(object):
         :type client: Client
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2203,7 +2216,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_client_model_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_client_model_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.test_client_model_with_http_info(client, **kwargs)  # noqa: E501
@@ -2224,7 +2238,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2349,10 +2363,10 @@ class FakeApi(object):
         :type str_query: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2360,7 +2374,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_date_time_query_parameter_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_date_time_query_parameter_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.test_date_time_query_parameter_with_http_info(date_time_query, str_query, **kwargs)  # noqa: E501
@@ -2382,7 +2397,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2528,10 +2543,10 @@ class FakeApi(object):
         :type param_callback: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2539,7 +2554,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_endpoint_parameters_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_endpoint_parameters_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.test_endpoint_parameters_with_http_info(number, double, pattern_without_delimiter, byte, integer, int32, int64, float, string, binary, byte_with_max_length, var_date, date_time, password, param_callback, **kwargs)  # noqa: E501
@@ -2588,7 +2604,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2772,10 +2788,10 @@ class FakeApi(object):
         :type int64_group: int
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2783,7 +2799,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_group_parameters_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_group_parameters_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.test_group_parameters_with_http_info(required_string_group, required_boolean_group, required_int64_group, string_group, boolean_group, int64_group, **kwargs)  # noqa: E501
@@ -2814,7 +2831,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2945,10 +2962,10 @@ class FakeApi(object):
         :type request_body: Dict[str, str]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2956,7 +2973,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_inline_additional_properties_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_inline_additional_properties_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.test_inline_additional_properties_with_http_info(request_body, **kwargs)  # noqa: E501
@@ -2977,7 +2995,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -3097,10 +3115,10 @@ class FakeApi(object):
         :type param2: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -3108,7 +3126,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_json_form_data_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_json_form_data_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.test_json_form_data_with_http_info(param, param2, **kwargs)  # noqa: E501
@@ -3131,7 +3150,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -3265,10 +3284,10 @@ class FakeApi(object):
         :type language: Dict[str, str]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -3276,7 +3295,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_query_parameter_collection_format_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_query_parameter_collection_format_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.test_query_parameter_collection_format_with_http_info(pipe, ioutil, http, url, context, allow_empty, language, **kwargs)  # noqa: E501
@@ -3309,7 +3329,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/fake_classname_tags123_api.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/fake_classname_tags123_api.py
index 5f06bd394e8..1553c2d10b8 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/fake_classname_tags123_api.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/fake_classname_tags123_api.py
@@ -32,14 +32,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class FakeClassnameTags123Api(object):
+class FakeClassnameTags123Api:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -67,10 +67,10 @@ class FakeClassnameTags123Api(object):
         :type client: Client
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -78,7 +78,8 @@ class FakeClassnameTags123Api(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_classname_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_classname_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.test_classname_with_http_info(client, **kwargs)  # noqa: E501
@@ -99,7 +100,7 @@ class FakeClassnameTags123Api(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/pet_api.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/pet_api.py
index b3a44f89a80..21954fd08a9 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/pet_api.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/pet_api.py
@@ -35,14 +35,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class PetApi(object):
+class PetApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -70,10 +70,10 @@ class PetApi(object):
         :type pet: Pet
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -81,7 +81,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the add_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the add_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.add_pet_with_http_info(pet, **kwargs)  # noqa: E501
@@ -102,7 +103,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -222,10 +223,10 @@ class PetApi(object):
         :type api_key: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -233,7 +234,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the delete_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the delete_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.delete_pet_with_http_info(pet_id, api_key, **kwargs)  # noqa: E501
@@ -256,7 +258,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -371,10 +373,10 @@ class PetApi(object):
         :type status: List[str]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -382,7 +384,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the find_pets_by_status_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the find_pets_by_status_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.find_pets_by_status_with_http_info(status, **kwargs)  # noqa: E501
@@ -403,7 +406,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -522,10 +525,10 @@ class PetApi(object):
         :type tags: List[str]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -533,7 +536,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the find_pets_by_tags_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the find_pets_by_tags_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.find_pets_by_tags_with_http_info(tags, **kwargs)  # noqa: E501
@@ -554,7 +558,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -675,10 +679,10 @@ class PetApi(object):
         :type pet_id: int
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -686,7 +690,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the get_pet_by_id_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the get_pet_by_id_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.get_pet_by_id_with_http_info(pet_id, **kwargs)  # noqa: E501
@@ -707,7 +712,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -826,10 +831,10 @@ class PetApi(object):
         :type pet: Pet
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -837,7 +842,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the update_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the update_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.update_pet_with_http_info(pet, **kwargs)  # noqa: E501
@@ -858,7 +864,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -980,10 +986,10 @@ class PetApi(object):
         :type status: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -991,7 +997,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the update_pet_with_form_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the update_pet_with_form_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.update_pet_with_form_with_http_info(pet_id, name, status, **kwargs)  # noqa: E501
@@ -1016,7 +1023,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1146,10 +1153,10 @@ class PetApi(object):
         :type file: bytearray
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1157,7 +1164,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the upload_file_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the upload_file_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.upload_file_with_http_info(pet_id, additional_metadata, file, **kwargs)  # noqa: E501
@@ -1182,7 +1190,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1318,10 +1326,10 @@ class PetApi(object):
         :type additional_metadata: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1329,7 +1337,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the upload_file_with_required_file_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the upload_file_with_required_file_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.upload_file_with_required_file_with_http_info(pet_id, required_file, additional_metadata, **kwargs)  # noqa: E501
@@ -1354,7 +1363,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/store_api.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/store_api.py
index 4ad49674013..f1e80d7e27b 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/store_api.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/store_api.py
@@ -34,14 +34,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class StoreApi(object):
+class StoreApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -69,10 +69,10 @@ class StoreApi(object):
         :type order_id: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -80,7 +80,8 @@ class StoreApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the delete_order_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the delete_order_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.delete_order_with_http_info(order_id, **kwargs)  # noqa: E501
@@ -101,7 +102,7 @@ class StoreApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -210,10 +211,10 @@ class StoreApi(object):
 
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -221,7 +222,8 @@ class StoreApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the get_inventory_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the get_inventory_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.get_inventory_with_http_info(**kwargs)  # noqa: E501
@@ -240,7 +242,7 @@ class StoreApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -353,10 +355,10 @@ class StoreApi(object):
         :type order_id: int
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -364,7 +366,8 @@ class StoreApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the get_order_by_id_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the get_order_by_id_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.get_order_by_id_with_http_info(order_id, **kwargs)  # noqa: E501
@@ -385,7 +388,7 @@ class StoreApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -504,10 +507,10 @@ class StoreApi(object):
         :type order: Order
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -515,7 +518,8 @@ class StoreApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the place_order_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the place_order_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.place_order_with_http_info(order, **kwargs)  # noqa: E501
@@ -536,7 +540,7 @@ class StoreApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/user_api.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/user_api.py
index a54f051ed65..b17529a75a9 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/user_api.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api/user_api.py
@@ -32,14 +32,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class UserApi(object):
+class UserApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -67,10 +67,10 @@ class UserApi(object):
         :type user: User
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -78,7 +78,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the create_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the create_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.create_user_with_http_info(user, **kwargs)  # noqa: E501
@@ -99,7 +100,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -232,10 +233,10 @@ class UserApi(object):
         :type user: List[User]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -243,7 +244,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the create_users_with_array_input_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the create_users_with_array_input_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.create_users_with_array_input_with_http_info(user, **kwargs)  # noqa: E501
@@ -264,7 +266,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -382,10 +384,10 @@ class UserApi(object):
         :type user: List[User]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -393,7 +395,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the create_users_with_list_input_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the create_users_with_list_input_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.create_users_with_list_input_with_http_info(user, **kwargs)  # noqa: E501
@@ -414,7 +417,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -532,10 +535,10 @@ class UserApi(object):
         :type username: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -543,7 +546,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the delete_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the delete_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.delete_user_with_http_info(username, **kwargs)  # noqa: E501
@@ -564,7 +568,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -675,10 +679,10 @@ class UserApi(object):
         :type username: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -686,7 +690,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the get_user_by_name_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the get_user_by_name_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.get_user_by_name_with_http_info(username, **kwargs)  # noqa: E501
@@ -707,7 +712,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -828,10 +833,10 @@ class UserApi(object):
         :type password: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -839,7 +844,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the login_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the login_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.login_user_with_http_info(username, password, **kwargs)  # noqa: E501
@@ -862,7 +868,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -982,10 +988,10 @@ class UserApi(object):
 
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -993,7 +999,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the logout_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the logout_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.logout_user_with_http_info(**kwargs)  # noqa: E501
@@ -1012,7 +1019,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1121,10 +1128,10 @@ class UserApi(object):
         :type user: User
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1132,7 +1139,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the update_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the update_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         if async_req is not None:
             kwargs['async_req'] = async_req
         return self.update_user_with_http_info(username, user, **kwargs)  # noqa: E501
@@ -1155,7 +1163,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_client.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_client.py
index 66ae38bf984..a5cfc019588 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_client.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_client.py
@@ -31,7 +31,7 @@ from petstore_api import rest
 from petstore_api.exceptions import ApiValueError, ApiException
 
 
-class ApiClient(object):
+class ApiClient:
     """Generic API client for OpenAPI client library builds.
 
     OpenAPI generic API client. This client handles the client-
@@ -63,7 +63,7 @@ class ApiClient(object):
     _pool = None
 
     def __init__(self, configuration=None, header_name=None, header_value=None,
-                 cookie=None, pool_threads=1):
+                 cookie=None, pool_threads=1) -> None:
         # use default configuration if none is provided
         if configuration is None:
             configuration = Configuration.get_default()
@@ -330,7 +330,7 @@ class ApiClient(object):
         if data is None:
             return None
 
-        if type(klass) == str:
+        if isinstance(klass, str):
             if klass.startswith('List['):
                 sub_kls = re.match(r'List\[(.*)]', klass).group(1)
                 return [self.__deserialize(sub_data, sub_kls)
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_response.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_response.py
index d81c2ff5847..a0b62b95246 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_response.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/api_response.py
@@ -18,7 +18,7 @@ class ApiResponse:
                  status_code=None,
                  headers=None,
                  data=None,
-                 raw_data=None):
+                 raw_data=None) -> None:
         self.status_code = status_code
         self.headers = headers
         self.data = data
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/configuration.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/configuration.py
index 77d9071f79f..1e0b9acbc97 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/configuration.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/configuration.py
@@ -18,7 +18,6 @@ import sys
 import urllib3
 
 import http.client as httplib
-from petstore_api.exceptions import ApiValueError
 
 JSON_SCHEMA_VALIDATION_KEYWORDS = {
     'multipleOf', 'maximum', 'exclusiveMaximum',
@@ -26,7 +25,7 @@ JSON_SCHEMA_VALIDATION_KEYWORDS = {
     'minLength', 'pattern', 'maxItems', 'minItems'
 }
 
-class Configuration(object):
+class Configuration:
     """This class contains various settings of the API client.
 
     :param host: Base url.
@@ -50,7 +49,8 @@ class Configuration(object):
       configuration.
     :param server_operation_variables: Mapping from operation ID to a mapping with
       string values to replace variables in templated server configuration.
-      The validation of enums is performed for variables with defined enum values before.
+      The validation of enums is performed for variables with defined enum
+      values before.
     :param ssl_ca_cert: str - the path to a file of concatenated CA certificates
       in PEM format.
 
@@ -141,7 +141,7 @@ conf = petstore_api.Configuration(
                  server_index=None, server_variables=None,
                  server_operation_index=None, server_operation_variables=None,
                  ssl_ca_cert=None,
-                 ):
+                 ) -> None:
         """Constructor
         """
         self._base_path = "http://petstore.swagger.io:80/v2" if host is None else host
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/exceptions.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/exceptions.py
index 4c61edafeae..6c4ae9c4e02 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/exceptions.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/exceptions.py
@@ -18,7 +18,7 @@ class OpenApiException(Exception):
 
 class ApiTypeError(OpenApiException, TypeError):
     def __init__(self, msg, path_to_item=None, valid_classes=None,
-                 key_type=None):
+                 key_type=None) -> None:
         """ Raises an exception for TypeErrors
 
         Args:
@@ -46,7 +46,7 @@ class ApiTypeError(OpenApiException, TypeError):
 
 
 class ApiValueError(OpenApiException, ValueError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Args:
             msg (str): the exception message
@@ -64,7 +64,7 @@ class ApiValueError(OpenApiException, ValueError):
 
 
 class ApiAttributeError(OpenApiException, AttributeError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Raised when an attribute reference or assignment fails.
 
@@ -83,7 +83,7 @@ class ApiAttributeError(OpenApiException, AttributeError):
 
 
 class ApiKeyError(OpenApiException, KeyError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Args:
             msg (str): the exception message
@@ -101,7 +101,7 @@ class ApiKeyError(OpenApiException, KeyError):
 
 class ApiException(OpenApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         if http_resp:
             self.status = http_resp.status
             self.reason = http_resp.reason
@@ -128,30 +128,30 @@ class ApiException(OpenApiException):
 
 class BadRequestException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(BadRequestException, self).__init__(status, reason, http_resp)
 
 class NotFoundException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(NotFoundException, self).__init__(status, reason, http_resp)
 
 
 class UnauthorizedException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(UnauthorizedException, self).__init__(status, reason, http_resp)
 
 
 class ForbiddenException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(ForbiddenException, self).__init__(status, reason, http_resp)
 
 
 class ServiceException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(ServiceException, self).__init__(status, reason, http_resp)
 
 
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_color.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_color.py
index 61defc0e9eb..b422650686f 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_color.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_color.py
@@ -45,7 +45,7 @@ class AnyOfColor(BaseModel):
     class Config:
         validate_assignment = True
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_pig.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_pig.py
index c2f26f1e873..1254f6789a8 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_pig.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/any_of_pig.py
@@ -45,7 +45,7 @@ class AnyOfPig(BaseModel):
     class Config:
         validate_assignment = True
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/color.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/color.py
index eda8b56415e..4dee9419ab7 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/color.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/color.py
@@ -44,7 +44,7 @@ class Color(BaseModel):
     class Config:
         validate_assignment = True
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/int_or_string.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/int_or_string.py
index ef8444eec0d..5d5de47e305 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/int_or_string.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/int_or_string.py
@@ -42,7 +42,7 @@ class IntOrString(BaseModel):
     class Config:
         validate_assignment = True
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/one_of_enum_string.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/one_of_enum_string.py
index 282b555ca93..d7ae93ccb6a 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/one_of_enum_string.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/one_of_enum_string.py
@@ -44,7 +44,7 @@ class OneOfEnumString(BaseModel):
     class Config:
         validate_assignment = True
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/pig.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/pig.py
index dc8e394d689..1cb002bf6f7 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/pig.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/pig.py
@@ -47,7 +47,7 @@ class Pig(BaseModel):
     discriminator_value_class_map = {
     }
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/rest.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/rest.py
index d5c9ade5621..7daf8c921c8 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/rest.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/rest.py
@@ -28,7 +28,7 @@ logger = logging.getLogger(__name__)
 
 class RESTResponse(io.IOBase):
 
-    def __init__(self, resp, data):
+    def __init__(self, resp, data) -> None:
         self.aiohttp_response = resp
         self.status = resp.status
         self.reason = resp.reason
@@ -43,9 +43,9 @@ class RESTResponse(io.IOBase):
         return self.aiohttp_response.headers.get(name, default)
 
 
-class RESTClientObject(object):
+class RESTClientObject:
 
-    def __init__(self, configuration, pools_size=4, maxsize=None):
+    def __init__(self, configuration, pools_size=4, maxsize=None) -> None:
 
         # maxsize is number of requests to host that are allowed in parallel
         if maxsize is None:
diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/signing.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/signing.py
index a1b08b0b356..ec4d7d2a67f 100644
--- a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/signing.py
+++ b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/signing.py
@@ -66,7 +66,7 @@ HASH_SHA256 = 'sha256'
 HASH_SHA512 = 'sha512'
 
 
-class HttpSigningConfiguration(object):
+class HttpSigningConfiguration:
     """The configuration parameters for the HTTP signature security scheme.
     The HTTP signature security scheme is used to sign HTTP requests with a private key
     which is in possession of the API client.
@@ -122,7 +122,7 @@ class HttpSigningConfiguration(object):
                  signed_headers=None,
                  signing_algorithm=None,
                  hash_algorithm=None,
-                 signature_max_validity=None):
+                 signature_max_validity=None) -> None:
         self.key_id = key_id
         if signing_scheme not in {SCHEME_HS2019, SCHEME_RSA_SHA256, SCHEME_RSA_SHA512}:
             raise Exception("Unsupported security scheme: {0}".format(signing_scheme))
diff --git a/samples/openapi3/client/petstore/python/petstore_api/api/another_fake_api.py b/samples/openapi3/client/petstore/python/petstore_api/api/another_fake_api.py
index 8599ca98bbf..13a77052ca0 100755
--- a/samples/openapi3/client/petstore/python/petstore_api/api/another_fake_api.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/api/another_fake_api.py
@@ -31,14 +31,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class AnotherFakeApi(object):
+class AnotherFakeApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -58,10 +58,10 @@ class AnotherFakeApi(object):
         :type client: Client
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -69,7 +69,8 @@ class AnotherFakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the call_123_test_special_tags_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the call_123_test_special_tags_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.call_123_test_special_tags_with_http_info(client, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -88,7 +89,7 @@ class AnotherFakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python/petstore_api/api/default_api.py b/samples/openapi3/client/petstore/python/petstore_api/api/default_api.py
index 3ef7887aa61..3b615de2250 100755
--- a/samples/openapi3/client/petstore/python/petstore_api/api/default_api.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/api/default_api.py
@@ -29,14 +29,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class DefaultApi(object):
+class DefaultApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -53,10 +53,10 @@ class DefaultApi(object):
 
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -64,7 +64,8 @@ class DefaultApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the foo_get_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the foo_get_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.foo_get_with_http_info(**kwargs)  # noqa: E501
 
     @validate_arguments
@@ -80,7 +81,7 @@ class DefaultApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python/petstore_api/api/fake_api.py b/samples/openapi3/client/petstore/python/petstore_api/api/fake_api.py
index 24fd078e45a..16378e0d38f 100755
--- a/samples/openapi3/client/petstore/python/petstore_api/api/fake_api.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/api/fake_api.py
@@ -43,14 +43,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class FakeApi(object):
+class FakeApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -69,10 +69,10 @@ class FakeApi(object):
         :type body: object
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -80,7 +80,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_any_type_request_body_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_any_type_request_body_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.fake_any_type_request_body_with_http_info(body, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -98,7 +99,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -207,10 +208,10 @@ class FakeApi(object):
         :type enum_ref: EnumClass
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -218,7 +219,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_enum_ref_query_parameter_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_enum_ref_query_parameter_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.fake_enum_ref_query_parameter_with_http_info(enum_ref, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -236,7 +238,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -336,10 +338,10 @@ class FakeApi(object):
 
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -347,7 +349,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_health_get_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_health_get_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.fake_health_get_with_http_info(**kwargs)  # noqa: E501
 
     @validate_arguments
@@ -363,7 +366,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -471,10 +474,10 @@ class FakeApi(object):
         :type header_1: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -482,7 +485,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_http_signature_test_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_http_signature_test_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.fake_http_signature_test_with_http_info(pet, query_1, header_1, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -504,7 +508,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -622,10 +626,10 @@ class FakeApi(object):
         :type body: bool
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -633,7 +637,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_outer_boolean_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_outer_boolean_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.fake_outer_boolean_serialize_with_http_info(body, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -652,7 +657,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -768,10 +773,10 @@ class FakeApi(object):
         :type outer_composite: OuterComposite
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -779,7 +784,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_outer_composite_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_outer_composite_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.fake_outer_composite_serialize_with_http_info(outer_composite, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -798,7 +804,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -914,10 +920,10 @@ class FakeApi(object):
         :type body: float
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -925,7 +931,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_outer_number_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_outer_number_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.fake_outer_number_serialize_with_http_info(body, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -944,7 +951,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1060,10 +1067,10 @@ class FakeApi(object):
         :type body: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1071,7 +1078,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_outer_string_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_outer_string_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.fake_outer_string_serialize_with_http_info(body, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -1090,7 +1098,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1206,10 +1214,10 @@ class FakeApi(object):
         :type outer_object_with_enum_property: OuterObjectWithEnumProperty
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1217,7 +1225,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_property_enum_integer_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_property_enum_integer_serialize_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.fake_property_enum_integer_serialize_with_http_info(outer_object_with_enum_property, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -1236,7 +1245,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1349,10 +1358,10 @@ class FakeApi(object):
 
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1360,7 +1369,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the fake_return_list_of_objects_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the fake_return_list_of_objects_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.fake_return_list_of_objects_with_http_info(**kwargs)  # noqa: E501
 
     @validate_arguments
@@ -1376,7 +1386,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1612,10 +1622,10 @@ class FakeApi(object):
         :type body: bytearray
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1623,7 +1633,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_body_with_binary_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_body_with_binary_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_body_with_binary_with_http_info(body, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -1642,7 +1653,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1757,10 +1768,10 @@ class FakeApi(object):
         :type file_schema_test_class: FileSchemaTestClass
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1768,7 +1779,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_body_with_file_schema_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_body_with_file_schema_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_body_with_file_schema_with_http_info(file_schema_test_class, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -1787,7 +1799,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1898,10 +1910,10 @@ class FakeApi(object):
         :type user: User
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1909,7 +1921,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_body_with_query_params_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_body_with_query_params_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_body_with_query_params_with_http_info(query, user, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -1929,7 +1942,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2043,10 +2056,10 @@ class FakeApi(object):
         :type client: Client
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2054,7 +2067,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_client_model_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_client_model_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_client_model_with_http_info(client, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -2073,7 +2087,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2190,10 +2204,10 @@ class FakeApi(object):
         :type str_query: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2201,7 +2215,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_date_time_query_parameter_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_date_time_query_parameter_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_date_time_query_parameter_with_http_info(date_time_query, str_query, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -2221,7 +2236,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2359,10 +2374,10 @@ class FakeApi(object):
         :type param_callback: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2370,7 +2385,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_endpoint_parameters_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_endpoint_parameters_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_endpoint_parameters_with_http_info(number, double, pattern_without_delimiter, byte, integer, int32, int64, float, string, binary, byte_with_max_length, var_date, date_time, password, param_callback, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -2417,7 +2433,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2593,10 +2609,10 @@ class FakeApi(object):
         :type int64_group: int
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2604,7 +2620,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_group_parameters_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_group_parameters_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_group_parameters_with_http_info(required_string_group, required_boolean_group, required_int64_group, string_group, boolean_group, int64_group, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -2633,7 +2650,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2756,10 +2773,10 @@ class FakeApi(object):
         :type request_body: Dict[str, str]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2767,7 +2784,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_inline_additional_properties_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_inline_additional_properties_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_inline_additional_properties_with_http_info(request_body, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -2786,7 +2804,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -2898,10 +2916,10 @@ class FakeApi(object):
         :type param2: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -2909,7 +2927,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_json_form_data_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_json_form_data_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_json_form_data_with_http_info(param, param2, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -2930,7 +2949,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -3056,10 +3075,10 @@ class FakeApi(object):
         :type language: Dict[str, str]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -3067,7 +3086,8 @@ class FakeApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_query_parameter_collection_format_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_query_parameter_collection_format_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_query_parameter_collection_format_with_http_info(pipe, ioutil, http, url, context, allow_empty, language, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -3098,7 +3118,7 @@ class FakeApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python/petstore_api/api/fake_classname_tags123_api.py b/samples/openapi3/client/petstore/python/petstore_api/api/fake_classname_tags123_api.py
index d30572a41ea..56620e1baa2 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/api/fake_classname_tags123_api.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/api/fake_classname_tags123_api.py
@@ -31,14 +31,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class FakeClassnameTags123Api(object):
+class FakeClassnameTags123Api:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -58,10 +58,10 @@ class FakeClassnameTags123Api(object):
         :type client: Client
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -69,7 +69,8 @@ class FakeClassnameTags123Api(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the test_classname_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the test_classname_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.test_classname_with_http_info(client, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -88,7 +89,7 @@ class FakeClassnameTags123Api(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python/petstore_api/api/pet_api.py b/samples/openapi3/client/petstore/python/petstore_api/api/pet_api.py
index fc6a0250503..0325f335357 100755
--- a/samples/openapi3/client/petstore/python/petstore_api/api/pet_api.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/api/pet_api.py
@@ -34,14 +34,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class PetApi(object):
+class PetApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -61,10 +61,10 @@ class PetApi(object):
         :type pet: Pet
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -72,7 +72,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the add_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the add_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.add_pet_with_http_info(pet, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -91,7 +92,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -203,10 +204,10 @@ class PetApi(object):
         :type api_key: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -214,7 +215,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the delete_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the delete_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.delete_pet_with_http_info(pet_id, api_key, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -235,7 +237,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -342,10 +344,10 @@ class PetApi(object):
         :type status: List[str]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -353,7 +355,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the find_pets_by_status_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the find_pets_by_status_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.find_pets_by_status_with_http_info(status, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -372,7 +375,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -483,10 +486,10 @@ class PetApi(object):
         :type tags: List[str]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -494,7 +497,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the find_pets_by_tags_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the find_pets_by_tags_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.find_pets_by_tags_with_http_info(tags, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -513,7 +517,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -626,10 +630,10 @@ class PetApi(object):
         :type pet_id: int
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -637,7 +641,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the get_pet_by_id_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the get_pet_by_id_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.get_pet_by_id_with_http_info(pet_id, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -656,7 +661,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -767,10 +772,10 @@ class PetApi(object):
         :type pet: Pet
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -778,7 +783,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the update_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the update_pet_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.update_pet_with_http_info(pet, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -797,7 +803,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -911,10 +917,10 @@ class PetApi(object):
         :type status: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -922,7 +928,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the update_pet_with_form_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the update_pet_with_form_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.update_pet_with_form_with_http_info(pet_id, name, status, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -945,7 +952,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1067,10 +1074,10 @@ class PetApi(object):
         :type file: bytearray
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1078,7 +1085,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the upload_file_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the upload_file_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.upload_file_with_http_info(pet_id, additional_metadata, file, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -1101,7 +1109,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1229,10 +1237,10 @@ class PetApi(object):
         :type additional_metadata: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1240,7 +1248,8 @@ class PetApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the upload_file_with_required_file_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the upload_file_with_required_file_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.upload_file_with_required_file_with_http_info(pet_id, required_file, additional_metadata, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -1263,7 +1272,7 @@ class PetApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python/petstore_api/api/store_api.py b/samples/openapi3/client/petstore/python/petstore_api/api/store_api.py
index 11e41480d1b..9ccbc98603d 100755
--- a/samples/openapi3/client/petstore/python/petstore_api/api/store_api.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/api/store_api.py
@@ -33,14 +33,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class StoreApi(object):
+class StoreApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -60,10 +60,10 @@ class StoreApi(object):
         :type order_id: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -71,7 +71,8 @@ class StoreApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the delete_order_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the delete_order_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.delete_order_with_http_info(order_id, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -90,7 +91,7 @@ class StoreApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -191,10 +192,10 @@ class StoreApi(object):
 
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -202,7 +203,8 @@ class StoreApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the get_inventory_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the get_inventory_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.get_inventory_with_http_info(**kwargs)  # noqa: E501
 
     @validate_arguments
@@ -219,7 +221,7 @@ class StoreApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -324,10 +326,10 @@ class StoreApi(object):
         :type order_id: int
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -335,7 +337,8 @@ class StoreApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the get_order_by_id_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the get_order_by_id_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.get_order_by_id_with_http_info(order_id, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -354,7 +357,7 @@ class StoreApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -465,10 +468,10 @@ class StoreApi(object):
         :type order: Order
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -476,7 +479,8 @@ class StoreApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the place_order_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the place_order_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.place_order_with_http_info(order, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -495,7 +499,7 @@ class StoreApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python/petstore_api/api/user_api.py b/samples/openapi3/client/petstore/python/petstore_api/api/user_api.py
index 8761c5e5b35..3bb8e99417d 100755
--- a/samples/openapi3/client/petstore/python/petstore_api/api/user_api.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/api/user_api.py
@@ -31,14 +31,14 @@ from petstore_api.exceptions import (  # noqa: F401
 )
 
 
-class UserApi(object):
+class UserApi:
     """NOTE: This class is auto generated by OpenAPI Generator
     Ref: https://openapi-generator.tech
 
     Do not edit the class manually.
     """
 
-    def __init__(self, api_client=None):
+    def __init__(self, api_client=None) -> None:
         if api_client is None:
             api_client = ApiClient.get_default()
         self.api_client = api_client
@@ -58,10 +58,10 @@ class UserApi(object):
         :type user: User
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -69,7 +69,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the create_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the create_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.create_user_with_http_info(user, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -88,7 +89,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -213,10 +214,10 @@ class UserApi(object):
         :type user: List[User]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -224,7 +225,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the create_users_with_array_input_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the create_users_with_array_input_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.create_users_with_array_input_with_http_info(user, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -243,7 +245,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -353,10 +355,10 @@ class UserApi(object):
         :type user: List[User]
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -364,7 +366,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the create_users_with_list_input_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the create_users_with_list_input_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.create_users_with_list_input_with_http_info(user, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -383,7 +386,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -493,10 +496,10 @@ class UserApi(object):
         :type username: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -504,7 +507,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the delete_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the delete_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.delete_user_with_http_info(username, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -523,7 +527,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -626,10 +630,10 @@ class UserApi(object):
         :type username: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -637,7 +641,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the get_user_by_name_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the get_user_by_name_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.get_user_by_name_with_http_info(username, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -656,7 +661,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -769,10 +774,10 @@ class UserApi(object):
         :type password: str
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -780,7 +785,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the login_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the login_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.login_user_with_http_info(username, password, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -801,7 +807,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -913,10 +919,10 @@ class UserApi(object):
 
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -924,7 +930,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the logout_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the logout_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.logout_user_with_http_info(**kwargs)  # noqa: E501
 
     @validate_arguments
@@ -941,7 +948,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
@@ -1042,10 +1049,10 @@ class UserApi(object):
         :type user: User
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
-        :param _request_timeout: timeout setting for this request. If one
-                                 number provided, it will be total request
-                                 timeout. It can also be a pair (tuple) of
-                                 (connection, read) timeouts.
+        :param _request_timeout: timeout setting for this request.
+               If one number provided, it will be total request
+               timeout. It can also be a pair (tuple) of
+               (connection, read) timeouts.
         :return: Returns the result object.
                  If the method is called asynchronously,
                  returns the request thread.
@@ -1053,7 +1060,8 @@ class UserApi(object):
         """
         kwargs['_return_http_data_only'] = True
         if '_preload_content' in kwargs:
-            raise ValueError("Error! Please call the update_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data")
+            message = "Error! Please call the update_user_with_http_info method with `_preload_content` instead and obtain raw data from ApiResponse.raw_data"  # noqa: E501
+            raise ValueError(message)
         return self.update_user_with_http_info(username, user, **kwargs)  # noqa: E501
 
     @validate_arguments
@@ -1074,7 +1082,7 @@ class UserApi(object):
         :param async_req: Whether to execute the request asynchronously.
         :type async_req: bool, optional
         :param _preload_content: if False, the ApiResponse.data will
-                                 be set to none and raw_data will store the 
+                                 be set to none and raw_data will store the
                                  HTTP response body without reading/decoding.
                                  Default is True.
         :type _preload_content: bool, optional
diff --git a/samples/openapi3/client/petstore/python/petstore_api/api_client.py b/samples/openapi3/client/petstore/python/petstore_api/api_client.py
index 9fbad9a8d76..e01b84dfd5b 100755
--- a/samples/openapi3/client/petstore/python/petstore_api/api_client.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/api_client.py
@@ -31,7 +31,7 @@ from petstore_api import rest
 from petstore_api.exceptions import ApiValueError, ApiException
 
 
-class ApiClient(object):
+class ApiClient:
     """Generic API client for OpenAPI client library builds.
 
     OpenAPI generic API client. This client handles the client-
@@ -63,7 +63,7 @@ class ApiClient(object):
     _pool = None
 
     def __init__(self, configuration=None, header_name=None, header_value=None,
-                 cookie=None, pool_threads=1):
+                 cookie=None, pool_threads=1) -> None:
         # use default configuration if none is provided
         if configuration is None:
             configuration = Configuration.get_default()
@@ -329,7 +329,7 @@ class ApiClient(object):
         if data is None:
             return None
 
-        if type(klass) == str:
+        if isinstance(klass, str):
             if klass.startswith('List['):
                 sub_kls = re.match(r'List\[(.*)]', klass).group(1)
                 return [self.__deserialize(sub_data, sub_kls)
diff --git a/samples/openapi3/client/petstore/python/petstore_api/api_response.py b/samples/openapi3/client/petstore/python/petstore_api/api_response.py
index d81c2ff5847..a0b62b95246 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/api_response.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/api_response.py
@@ -18,7 +18,7 @@ class ApiResponse:
                  status_code=None,
                  headers=None,
                  data=None,
-                 raw_data=None):
+                 raw_data=None) -> None:
         self.status_code = status_code
         self.headers = headers
         self.data = data
diff --git a/samples/openapi3/client/petstore/python/petstore_api/configuration.py b/samples/openapi3/client/petstore/python/petstore_api/configuration.py
index bc222ed9c00..8bca6dc7ab0 100755
--- a/samples/openapi3/client/petstore/python/petstore_api/configuration.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/configuration.py
@@ -19,7 +19,6 @@ import sys
 import urllib3
 
 import http.client as httplib
-from petstore_api.exceptions import ApiValueError
 
 JSON_SCHEMA_VALIDATION_KEYWORDS = {
     'multipleOf', 'maximum', 'exclusiveMaximum',
@@ -27,7 +26,7 @@ JSON_SCHEMA_VALIDATION_KEYWORDS = {
     'minLength', 'pattern', 'maxItems', 'minItems'
 }
 
-class Configuration(object):
+class Configuration:
     """This class contains various settings of the API client.
 
     :param host: Base url.
@@ -51,7 +50,8 @@ class Configuration(object):
       configuration.
     :param server_operation_variables: Mapping from operation ID to a mapping with
       string values to replace variables in templated server configuration.
-      The validation of enums is performed for variables with defined enum values before.
+      The validation of enums is performed for variables with defined enum
+      values before.
     :param ssl_ca_cert: str - the path to a file of concatenated CA certificates
       in PEM format.
 
@@ -142,7 +142,7 @@ conf = petstore_api.Configuration(
                  server_index=None, server_variables=None,
                  server_operation_index=None, server_operation_variables=None,
                  ssl_ca_cert=None,
-                 ):
+                 ) -> None:
         """Constructor
         """
         self._base_path = "http://petstore.swagger.io:80/v2" if host is None else host
diff --git a/samples/openapi3/client/petstore/python/petstore_api/exceptions.py b/samples/openapi3/client/petstore/python/petstore_api/exceptions.py
index 4c61edafeae..6c4ae9c4e02 100755
--- a/samples/openapi3/client/petstore/python/petstore_api/exceptions.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/exceptions.py
@@ -18,7 +18,7 @@ class OpenApiException(Exception):
 
 class ApiTypeError(OpenApiException, TypeError):
     def __init__(self, msg, path_to_item=None, valid_classes=None,
-                 key_type=None):
+                 key_type=None) -> None:
         """ Raises an exception for TypeErrors
 
         Args:
@@ -46,7 +46,7 @@ class ApiTypeError(OpenApiException, TypeError):
 
 
 class ApiValueError(OpenApiException, ValueError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Args:
             msg (str): the exception message
@@ -64,7 +64,7 @@ class ApiValueError(OpenApiException, ValueError):
 
 
 class ApiAttributeError(OpenApiException, AttributeError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Raised when an attribute reference or assignment fails.
 
@@ -83,7 +83,7 @@ class ApiAttributeError(OpenApiException, AttributeError):
 
 
 class ApiKeyError(OpenApiException, KeyError):
-    def __init__(self, msg, path_to_item=None):
+    def __init__(self, msg, path_to_item=None) -> None:
         """
         Args:
             msg (str): the exception message
@@ -101,7 +101,7 @@ class ApiKeyError(OpenApiException, KeyError):
 
 class ApiException(OpenApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         if http_resp:
             self.status = http_resp.status
             self.reason = http_resp.reason
@@ -128,30 +128,30 @@ class ApiException(OpenApiException):
 
 class BadRequestException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(BadRequestException, self).__init__(status, reason, http_resp)
 
 class NotFoundException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(NotFoundException, self).__init__(status, reason, http_resp)
 
 
 class UnauthorizedException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(UnauthorizedException, self).__init__(status, reason, http_resp)
 
 
 class ForbiddenException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(ForbiddenException, self).__init__(status, reason, http_resp)
 
 
 class ServiceException(ApiException):
 
-    def __init__(self, status=None, reason=None, http_resp=None):
+    def __init__(self, status=None, reason=None, http_resp=None) -> None:
         super(ServiceException, self).__init__(status, reason, http_resp)
 
 
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/any_of_color.py b/samples/openapi3/client/petstore/python/petstore_api/models/any_of_color.py
index 61defc0e9eb..b422650686f 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/any_of_color.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/any_of_color.py
@@ -45,7 +45,7 @@ class AnyOfColor(BaseModel):
     class Config:
         validate_assignment = True
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/any_of_pig.py b/samples/openapi3/client/petstore/python/petstore_api/models/any_of_pig.py
index c2f26f1e873..1254f6789a8 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/any_of_pig.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/any_of_pig.py
@@ -45,7 +45,7 @@ class AnyOfPig(BaseModel):
     class Config:
         validate_assignment = True
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/color.py b/samples/openapi3/client/petstore/python/petstore_api/models/color.py
index eda8b56415e..4dee9419ab7 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/color.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/color.py
@@ -44,7 +44,7 @@ class Color(BaseModel):
     class Config:
         validate_assignment = True
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/int_or_string.py b/samples/openapi3/client/petstore/python/petstore_api/models/int_or_string.py
index ef8444eec0d..5d5de47e305 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/int_or_string.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/int_or_string.py
@@ -42,7 +42,7 @@ class IntOrString(BaseModel):
     class Config:
         validate_assignment = True
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/one_of_enum_string.py b/samples/openapi3/client/petstore/python/petstore_api/models/one_of_enum_string.py
index 282b555ca93..d7ae93ccb6a 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/one_of_enum_string.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/one_of_enum_string.py
@@ -44,7 +44,7 @@ class OneOfEnumString(BaseModel):
     class Config:
         validate_assignment = True
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python/petstore_api/models/pig.py b/samples/openapi3/client/petstore/python/petstore_api/models/pig.py
index 1f84dd6c271..62ae5a2a0ef 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/models/pig.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/models/pig.py
@@ -47,7 +47,7 @@ class Pig(BaseModel):
     discriminator_value_class_map = {
     }
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
         if args:
             if len(args) > 1:
                 raise ValueError("If a position argument is used, only 1 is allowed to set `actual_instance`")
diff --git a/samples/openapi3/client/petstore/python/petstore_api/rest.py b/samples/openapi3/client/petstore/python/petstore_api/rest.py
index a2bf1826966..df9aca00804 100755
--- a/samples/openapi3/client/petstore/python/petstore_api/rest.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/rest.py
@@ -29,7 +29,7 @@ logger = logging.getLogger(__name__)
 
 class RESTResponse(io.IOBase):
 
-    def __init__(self, resp):
+    def __init__(self, resp) -> None:
         self.urllib3_response = resp
         self.status = resp.status
         self.reason = resp.reason
@@ -44,9 +44,9 @@ class RESTResponse(io.IOBase):
         return self.urllib3_response.headers.get(name, default)
 
 
-class RESTClientObject(object):
+class RESTClientObject:
 
-    def __init__(self, configuration, pools_size=4, maxsize=None):
+    def __init__(self, configuration, pools_size=4, maxsize=None) -> None:
         # urllib3.PoolManager will pass all kw parameters to connectionpool
         # https://github.com/shazow/urllib3/blob/f9409436f83aeb79fbaf090181cd81b784f1b8ce/urllib3/poolmanager.py#L75  # noqa: E501
         # https://github.com/shazow/urllib3/blob/f9409436f83aeb79fbaf090181cd81b784f1b8ce/urllib3/connectionpool.py#L680  # noqa: E501
diff --git a/samples/openapi3/client/petstore/python/petstore_api/signing.py b/samples/openapi3/client/petstore/python/petstore_api/signing.py
index a1b08b0b356..ec4d7d2a67f 100644
--- a/samples/openapi3/client/petstore/python/petstore_api/signing.py
+++ b/samples/openapi3/client/petstore/python/petstore_api/signing.py
@@ -66,7 +66,7 @@ HASH_SHA256 = 'sha256'
 HASH_SHA512 = 'sha512'
 
 
-class HttpSigningConfiguration(object):
+class HttpSigningConfiguration:
     """The configuration parameters for the HTTP signature security scheme.
     The HTTP signature security scheme is used to sign HTTP requests with a private key
     which is in possession of the API client.
@@ -122,7 +122,7 @@ class HttpSigningConfiguration(object):
                  signed_headers=None,
                  signing_algorithm=None,
                  hash_algorithm=None,
-                 signature_max_validity=None):
+                 signature_max_validity=None) -> None:
         self.key_id = key_id
         if signing_scheme not in {SCHEME_HS2019, SCHEME_RSA_SHA256, SCHEME_RSA_SHA512}:
             raise Exception("Unsupported security scheme: {0}".format(signing_scheme))