diff --git a/.gitignore b/.gitignore
index 1be33afa885..c9bf3b41fec 100644
--- a/.gitignore
+++ b/.gitignore
@@ -173,14 +173,13 @@ samples/client/petstore/csharp-refactor/OpenAPIClient/nuget.exe
 # Python
 *.pyc
 __pycache__
+.venv/
 samples/client/petstore/python/dev-requirements.txt.log
 samples/client/petstore/python/swagger_client.egg-info/SOURCES.txt
 samples/client/petstore/python/.coverage
 samples/client/petstore/python/.projectile
-samples/client/petstore/python/.venv/
-samples/client/petstore/python-asyncio/.venv/
 samples/client/petstore/python-asyncio/.pytest_cache/
-samples/client/petstore/python-tornado/.venv/
+
 
 # PHP
 samples/client/petstore/php/OpenAPIClient-php/composer.lock
diff --git a/modules/openapi-generator/src/main/resources/python-flask/__init__model.mustache b/modules/openapi-generator/src/main/resources/python-flask/__init__model.mustache
index 98b56e3d154..e39abfcf463 100644
--- a/modules/openapi-generator/src/main/resources/python-flask/__init__model.mustache
+++ b/modules/openapi-generator/src/main/resources/python-flask/__init__model.mustache
@@ -1,7 +1,4 @@
-# coding: utf-8
-
 # flake8: noqa
-from __future__ import absolute_import
 # import models into model package
 {{#models}}{{#model}}from {{modelPackage}}.{{classFilename}} import {{classname}}{{/model}}
 {{/models}}
\ No newline at end of file
diff --git a/modules/openapi-generator/src/main/resources/python-flask/base_model.mustache b/modules/openapi-generator/src/main/resources/python-flask/base_model.mustache
index c771c9e58d5..33b96e27b55 100644
--- a/modules/openapi-generator/src/main/resources/python-flask/base_model.mustache
+++ b/modules/openapi-generator/src/main/resources/python-flask/base_model.mustache
@@ -1,6 +1,5 @@
 import pprint
 
-import six
 import typing
 
 from {{packageName}} import util
@@ -8,7 +7,7 @@ from {{packageName}} import util
 T = typing.TypeVar('T')
 
 
-class Model(object):
+class Model:
     # openapiTypes: The key is attribute name and the
     # value is attribute type.
     openapi_types: typing.Dict[str, type] = {}
@@ -29,7 +28,7 @@ class Model(object):
         """
         result = {}
 
-        for attr, _ in six.iteritems(self.openapi_types):
+        for attr in self.openapi_types:
             value = getattr(self, attr)
             if isinstance(value, list):
                 result[attr] = list(map(
diff --git a/modules/openapi-generator/src/main/resources/python-flask/controller.mustache b/modules/openapi-generator/src/main/resources/python-flask/controller.mustache
index 9422589cc7c..ad276a661ad 100644
--- a/modules/openapi-generator/src/main/resources/python-flask/controller.mustache
+++ b/modules/openapi-generator/src/main/resources/python-flask/controller.mustache
@@ -1,5 +1,4 @@
 import connexion
-import six
 from typing import Dict
 from typing import Tuple
 from typing import Union
@@ -97,15 +96,15 @@ def {{operationId}}({{#allParams}}{{paramName}}{{^required}}=None{{/required}}{{
             {{#items}}
                 {{#isDate}}
     if connexion.request.is_json:
-        {{paramName}} = {k: util.deserialize_date(v) for k, v in six.iteritems(connexion.request.get_json())}  # noqa: E501
+        {{paramName}} = {k: util.deserialize_date(v) for k, v in connexion.request.get_json().items()}  # noqa: E501
                 {{/isDate}}
                 {{#isDateTime}}
     if connexion.request.is_json:
-        {{paramName}} = {k: util.deserialize_datetime(v) for k, v in six.iteritems(connexion.request.get_json())}  # noqa: E501
+        {{paramName}} = {k: util.deserialize_datetime(v) for k, v in connexion.request.get_json().items()}  # noqa: E501
                 {{/isDateTime}}
                 {{#complexType}}
     if connexion.request.is_json:
-        {{paramName}} = {k: {{baseType}}.from_dict(v) for k, v in six.iteritems(connexion.request.get_json())}  # noqa: E501
+        {{paramName}} = {k: {{baseType}}.from_dict(v) for k, v in connexion.request.get_json().items()}  # noqa: E501
                 {{/complexType}}
             {{/items}}
         {{/isMap}}
diff --git a/modules/openapi-generator/src/main/resources/python-flask/controller_test.mustache b/modules/openapi-generator/src/main/resources/python-flask/controller_test.mustache
index f8b8beff559..e98fbd30700 100644
--- a/modules/openapi-generator/src/main/resources/python-flask/controller_test.mustache
+++ b/modules/openapi-generator/src/main/resources/python-flask/controller_test.mustache
@@ -1,10 +1,6 @@
-# coding: utf-8
-
-from __future__ import absolute_import
 import unittest
 
 from flask import json
-from six import BytesIO
 
 {{#imports}}{{import}}  # noqa: E501
 {{/imports}}
diff --git a/modules/openapi-generator/src/main/resources/python-flask/encoder.mustache b/modules/openapi-generator/src/main/resources/python-flask/encoder.mustache
index 0021509ffc4..4d27ad24866 100644
--- a/modules/openapi-generator/src/main/resources/python-flask/encoder.mustache
+++ b/modules/openapi-generator/src/main/resources/python-flask/encoder.mustache
@@ -1,5 +1,4 @@
 from connexion.apps.flask_app import FlaskJSONEncoder
-import six
 
 from {{modelPackage}}.base_model import Model
 
@@ -10,7 +9,7 @@ class JSONEncoder(FlaskJSONEncoder):
     def default(self, o):
         if isinstance(o, Model):
             dikt = {}
-            for attr, _ in six.iteritems(o.openapi_types):
+            for attr in o.openapi_types:
                 value = getattr(o, attr)
                 if value is None and not self.include_nulls:
                     continue
diff --git a/modules/openapi-generator/src/main/resources/python-flask/model.mustache b/modules/openapi-generator/src/main/resources/python-flask/model.mustache
index b790e80f187..4e7ecde8ef2 100644
--- a/modules/openapi-generator/src/main/resources/python-flask/model.mustache
+++ b/modules/openapi-generator/src/main/resources/python-flask/model.mustache
@@ -1,6 +1,3 @@
-# coding: utf-8
-
-from __future__ import absolute_import
 from datetime import date, datetime  # noqa: F401
 
 from typing import List, Dict  # noqa: F401
diff --git a/modules/openapi-generator/src/main/resources/python-flask/setup.mustache b/modules/openapi-generator/src/main/resources/python-flask/setup.mustache
index ec06a7798b2..00dd770077b 100644
--- a/modules/openapi-generator/src/main/resources/python-flask/setup.mustache
+++ b/modules/openapi-generator/src/main/resources/python-flask/setup.mustache
@@ -1,5 +1,3 @@
-# coding: utf-8
-
 import sys
 from setuptools import setup, find_packages
 
diff --git a/modules/openapi-generator/src/main/resources/python-flask/typing_utils.mustache b/modules/openapi-generator/src/main/resources/python-flask/typing_utils.mustache
index 0563f81fd53..74e3c913a7d 100644
--- a/modules/openapi-generator/src/main/resources/python-flask/typing_utils.mustache
+++ b/modules/openapi-generator/src/main/resources/python-flask/typing_utils.mustache
@@ -1,5 +1,3 @@
-# coding: utf-8
-
 import sys
 
 if sys.version_info < (3, 7):
diff --git a/modules/openapi-generator/src/main/resources/python-flask/util.mustache b/modules/openapi-generator/src/main/resources/python-flask/util.mustache
index 60ebebac8e1..5f2f4539e22 100644
--- a/modules/openapi-generator/src/main/resources/python-flask/util.mustache
+++ b/modules/openapi-generator/src/main/resources/python-flask/util.mustache
@@ -1,6 +1,5 @@
 import datetime
 
-import six
 import typing
 from {{packageName}} import typing_utils
 
@@ -16,7 +15,7 @@ def _deserialize(data, klass):
     if data is None:
         return None
 
-    if klass in six.integer_types or klass in (float, str, bool, bytearray):
+    if klass in (int, float, str, bool, bytearray):
         return _deserialize_primitive(data, klass)
     elif klass == object:
         return _deserialize_object(data)
@@ -45,7 +44,7 @@ def _deserialize_primitive(data, klass):
     try:
         value = klass(data)
     except UnicodeEncodeError:
-        value = six.u(data)
+        value = data
     except TypeError:
         value = data
     return value
@@ -110,7 +109,7 @@ def deserialize_model(data, klass):
     if not instance.openapi_types:
         return data
 
-    for attr, attr_type in six.iteritems(instance.openapi_types):
+    for attr, attr_type in instance.openapi_types.items():
         if data is not None \
                 and instance.attribute_map[attr] in data \
                 and isinstance(data, (list, dict)):
@@ -145,4 +144,4 @@ def _deserialize_dict(data, boxed_type):
     :rtype: dict
     """
     return {k: _deserialize(v, boxed_type)
-            for k, v in six.iteritems(data)}
+            for k, v in data.items() }
diff --git a/samples/server/petstore/python-flask/openapi_server/controllers/pet_controller.py b/samples/server/petstore/python-flask/openapi_server/controllers/pet_controller.py
index e31e316a07e..89086c54bd4 100644
--- a/samples/server/petstore/python-flask/openapi_server/controllers/pet_controller.py
+++ b/samples/server/petstore/python-flask/openapi_server/controllers/pet_controller.py
@@ -1,5 +1,4 @@
 import connexion
-import six
 from typing import Dict
 from typing import Tuple
 from typing import Union
diff --git a/samples/server/petstore/python-flask/openapi_server/controllers/store_controller.py b/samples/server/petstore/python-flask/openapi_server/controllers/store_controller.py
index 21bc29621fe..62887e7adac 100644
--- a/samples/server/petstore/python-flask/openapi_server/controllers/store_controller.py
+++ b/samples/server/petstore/python-flask/openapi_server/controllers/store_controller.py
@@ -1,5 +1,4 @@
 import connexion
-import six
 from typing import Dict
 from typing import Tuple
 from typing import Union
diff --git a/samples/server/petstore/python-flask/openapi_server/controllers/user_controller.py b/samples/server/petstore/python-flask/openapi_server/controllers/user_controller.py
index 8cd4edf68a2..0acef475150 100644
--- a/samples/server/petstore/python-flask/openapi_server/controllers/user_controller.py
+++ b/samples/server/petstore/python-flask/openapi_server/controllers/user_controller.py
@@ -1,5 +1,4 @@
 import connexion
-import six
 from typing import Dict
 from typing import Tuple
 from typing import Union
diff --git a/samples/server/petstore/python-flask/openapi_server/encoder.py b/samples/server/petstore/python-flask/openapi_server/encoder.py
index 1ec9cb99b83..60f4fa67e7d 100644
--- a/samples/server/petstore/python-flask/openapi_server/encoder.py
+++ b/samples/server/petstore/python-flask/openapi_server/encoder.py
@@ -1,5 +1,4 @@
 from connexion.apps.flask_app import FlaskJSONEncoder
-import six
 
 from openapi_server.models.base_model import Model
 
@@ -10,7 +9,7 @@ class JSONEncoder(FlaskJSONEncoder):
     def default(self, o):
         if isinstance(o, Model):
             dikt = {}
-            for attr, _ in six.iteritems(o.openapi_types):
+            for attr in o.openapi_types:
                 value = getattr(o, attr)
                 if value is None and not self.include_nulls:
                     continue
diff --git a/samples/server/petstore/python-flask/openapi_server/models/__init__.py b/samples/server/petstore/python-flask/openapi_server/models/__init__.py
index 962f6f34936..24ea9866d7b 100644
--- a/samples/server/petstore/python-flask/openapi_server/models/__init__.py
+++ b/samples/server/petstore/python-flask/openapi_server/models/__init__.py
@@ -1,7 +1,4 @@
-# coding: utf-8
-
 # flake8: noqa
-from __future__ import absolute_import
 # import models into model package
 from openapi_server.models.api_response import ApiResponse
 from openapi_server.models.category import Category
diff --git a/samples/server/petstore/python-flask/openapi_server/models/api_response.py b/samples/server/petstore/python-flask/openapi_server/models/api_response.py
index a795a0a2224..87801d39e32 100644
--- a/samples/server/petstore/python-flask/openapi_server/models/api_response.py
+++ b/samples/server/petstore/python-flask/openapi_server/models/api_response.py
@@ -1,6 +1,3 @@
-# coding: utf-8
-
-from __future__ import absolute_import
 from datetime import date, datetime  # noqa: F401
 
 from typing import List, Dict  # noqa: F401
diff --git a/samples/server/petstore/python-flask/openapi_server/models/base_model.py b/samples/server/petstore/python-flask/openapi_server/models/base_model.py
index 916e582ec27..c01b423a743 100644
--- a/samples/server/petstore/python-flask/openapi_server/models/base_model.py
+++ b/samples/server/petstore/python-flask/openapi_server/models/base_model.py
@@ -1,6 +1,5 @@
 import pprint
 
-import six
 import typing
 
 from openapi_server import util
@@ -8,7 +7,7 @@ from openapi_server import util
 T = typing.TypeVar('T')
 
 
-class Model(object):
+class Model:
     # openapiTypes: The key is attribute name and the
     # value is attribute type.
     openapi_types: typing.Dict[str, type] = {}
@@ -29,7 +28,7 @@ class Model(object):
         """
         result = {}
 
-        for attr, _ in six.iteritems(self.openapi_types):
+        for attr in self.openapi_types:
             value = getattr(self, attr)
             if isinstance(value, list):
                 result[attr] = list(map(
diff --git a/samples/server/petstore/python-flask/openapi_server/models/category.py b/samples/server/petstore/python-flask/openapi_server/models/category.py
index 5e068634926..222a30f6f28 100644
--- a/samples/server/petstore/python-flask/openapi_server/models/category.py
+++ b/samples/server/petstore/python-flask/openapi_server/models/category.py
@@ -1,6 +1,3 @@
-# coding: utf-8
-
-from __future__ import absolute_import
 from datetime import date, datetime  # noqa: F401
 
 from typing import List, Dict  # noqa: F401
diff --git a/samples/server/petstore/python-flask/openapi_server/models/order.py b/samples/server/petstore/python-flask/openapi_server/models/order.py
index b9b11b2b35a..b0df0613ccc 100644
--- a/samples/server/petstore/python-flask/openapi_server/models/order.py
+++ b/samples/server/petstore/python-flask/openapi_server/models/order.py
@@ -1,6 +1,3 @@
-# coding: utf-8
-
-from __future__ import absolute_import
 from datetime import date, datetime  # noqa: F401
 
 from typing import List, Dict  # noqa: F401
diff --git a/samples/server/petstore/python-flask/openapi_server/models/pet.py b/samples/server/petstore/python-flask/openapi_server/models/pet.py
index 1473099c5f8..57cbb673879 100644
--- a/samples/server/petstore/python-flask/openapi_server/models/pet.py
+++ b/samples/server/petstore/python-flask/openapi_server/models/pet.py
@@ -1,6 +1,3 @@
-# coding: utf-8
-
-from __future__ import absolute_import
 from datetime import date, datetime  # noqa: F401
 
 from typing import List, Dict  # noqa: F401
diff --git a/samples/server/petstore/python-flask/openapi_server/models/tag.py b/samples/server/petstore/python-flask/openapi_server/models/tag.py
index c4dfa927b86..1088ad71654 100644
--- a/samples/server/petstore/python-flask/openapi_server/models/tag.py
+++ b/samples/server/petstore/python-flask/openapi_server/models/tag.py
@@ -1,6 +1,3 @@
-# coding: utf-8
-
-from __future__ import absolute_import
 from datetime import date, datetime  # noqa: F401
 
 from typing import List, Dict  # noqa: F401
diff --git a/samples/server/petstore/python-flask/openapi_server/models/user.py b/samples/server/petstore/python-flask/openapi_server/models/user.py
index 8ed94b32f48..e8e31169954 100644
--- a/samples/server/petstore/python-flask/openapi_server/models/user.py
+++ b/samples/server/petstore/python-flask/openapi_server/models/user.py
@@ -1,6 +1,3 @@
-# coding: utf-8
-
-from __future__ import absolute_import
 from datetime import date, datetime  # noqa: F401
 
 from typing import List, Dict  # noqa: F401
diff --git a/samples/server/petstore/python-flask/openapi_server/test/test_pet_controller.py b/samples/server/petstore/python-flask/openapi_server/test/test_pet_controller.py
index d1eb1d32668..a62cb03709c 100644
--- a/samples/server/petstore/python-flask/openapi_server/test/test_pet_controller.py
+++ b/samples/server/petstore/python-flask/openapi_server/test/test_pet_controller.py
@@ -1,10 +1,6 @@
-# coding: utf-8
-
-from __future__ import absolute_import
 import unittest
 
 from flask import json
-from six import BytesIO
 
 from openapi_server.models.api_response import ApiResponse  # noqa: E501
 from openapi_server.models.pet import Pet  # noqa: E501
@@ -20,23 +16,7 @@ class TestPetController(BaseTestCase):
 
         Add a new pet to the store
         """
-        body = {
-  "photoUrls" : [ "photoUrls", "photoUrls" ],
-  "name" : "doggie",
-  "id" : 0,
-  "category" : {
-    "name" : "name",
-    "id" : 6
-  },
-  "tags" : [ {
-    "name" : "name",
-    "id" : 1
-  }, {
-    "name" : "name",
-    "id" : 1
-  } ],
-  "status" : "available"
-}
+        body = {"photoUrls":["photoUrls","photoUrls"],"name":"doggie","id":0,"category":{"name":"name","id":6},"tags":[{"name":"name","id":1},{"name":"name","id":1}],"status":"available"}
         headers = { 
             'Content-Type': 'application/json',
             'Authorization': 'Bearer special-key',
@@ -71,7 +51,7 @@ class TestPetController(BaseTestCase):
 
         Finds Pets by status
         """
-        query_string = [('status', 'available')]
+        query_string = [('status', ['status_example'])]
         headers = { 
             'Accept': 'application/json',
             'Authorization': 'Bearer special-key',
@@ -124,23 +104,7 @@ class TestPetController(BaseTestCase):
 
         Update an existing pet
         """
-        body = {
-  "photoUrls" : [ "photoUrls", "photoUrls" ],
-  "name" : "doggie",
-  "id" : 0,
-  "category" : {
-    "name" : "name",
-    "id" : 6
-  },
-  "tags" : [ {
-    "name" : "name",
-    "id" : 1
-  }, {
-    "name" : "name",
-    "id" : 1
-  } ],
-  "status" : "available"
-}
+        body = {"photoUrls":["photoUrls","photoUrls"],"name":"doggie","id":0,"category":{"name":"name","id":6},"tags":[{"name":"name","id":1},{"name":"name","id":1}],"status":"available"}
         headers = { 
             'Content-Type': 'application/json',
             'Authorization': 'Bearer special-key',
diff --git a/samples/server/petstore/python-flask/openapi_server/test/test_store_controller.py b/samples/server/petstore/python-flask/openapi_server/test/test_store_controller.py
index 43867b1d98e..36b656cd827 100644
--- a/samples/server/petstore/python-flask/openapi_server/test/test_store_controller.py
+++ b/samples/server/petstore/python-flask/openapi_server/test/test_store_controller.py
@@ -1,10 +1,6 @@
-# coding: utf-8
-
-from __future__ import absolute_import
 import unittest
 
 from flask import json
-from six import BytesIO
 
 from openapi_server.models.order import Order  # noqa: E501
 from openapi_server.test import BaseTestCase
@@ -52,7 +48,7 @@ class TestStoreController(BaseTestCase):
             'Accept': 'application/json',
         }
         response = self.client.open(
-            '/v2/store/order/{order_id}'.format(order_id=1),
+            '/v2/store/order/{order_id}'.format(order_id=56),
             method='GET',
             headers=headers)
         self.assert200(response,
diff --git a/samples/server/petstore/python-flask/openapi_server/test/test_user_controller.py b/samples/server/petstore/python-flask/openapi_server/test/test_user_controller.py
index 010a72b0306..a991011b316 100644
--- a/samples/server/petstore/python-flask/openapi_server/test/test_user_controller.py
+++ b/samples/server/petstore/python-flask/openapi_server/test/test_user_controller.py
@@ -1,10 +1,6 @@
-# coding: utf-8
-
-from __future__ import absolute_import
 import unittest
 
 from flask import json
-from six import BytesIO
 
 from openapi_server.models.user import User  # noqa: E501
 from openapi_server.test import BaseTestCase
diff --git a/samples/server/petstore/python-flask/openapi_server/typing_utils.py b/samples/server/petstore/python-flask/openapi_server/typing_utils.py
index 0563f81fd53..74e3c913a7d 100644
--- a/samples/server/petstore/python-flask/openapi_server/typing_utils.py
+++ b/samples/server/petstore/python-flask/openapi_server/typing_utils.py
@@ -1,5 +1,3 @@
-# coding: utf-8
-
 import sys
 
 if sys.version_info < (3, 7):
diff --git a/samples/server/petstore/python-flask/openapi_server/util.py b/samples/server/petstore/python-flask/openapi_server/util.py
index 2a63f2109ba..bd83c5b330b 100644
--- a/samples/server/petstore/python-flask/openapi_server/util.py
+++ b/samples/server/petstore/python-flask/openapi_server/util.py
@@ -1,6 +1,5 @@
 import datetime
 
-import six
 import typing
 from openapi_server import typing_utils
 
@@ -16,7 +15,7 @@ def _deserialize(data, klass):
     if data is None:
         return None
 
-    if klass in six.integer_types or klass in (float, str, bool, bytearray):
+    if klass in (int, float, str, bool, bytearray):
         return _deserialize_primitive(data, klass)
     elif klass == object:
         return _deserialize_object(data)
@@ -45,7 +44,7 @@ def _deserialize_primitive(data, klass):
     try:
         value = klass(data)
     except UnicodeEncodeError:
-        value = six.u(data)
+        value = data
     except TypeError:
         value = data
     return value
@@ -110,7 +109,7 @@ def deserialize_model(data, klass):
     if not instance.openapi_types:
         return data
 
-    for attr, attr_type in six.iteritems(instance.openapi_types):
+    for attr, attr_type in instance.openapi_types.items():
         if data is not None \
                 and instance.attribute_map[attr] in data \
                 and isinstance(data, (list, dict)):
@@ -145,4 +144,4 @@ def _deserialize_dict(data, boxed_type):
     :rtype: dict
     """
     return {k: _deserialize(v, boxed_type)
-            for k, v in six.iteritems(data)}
+            for k, v in data.items() }
diff --git a/samples/server/petstore/python-flask/setup.py b/samples/server/petstore/python-flask/setup.py
index 1cd2660efd6..80284885589 100644
--- a/samples/server/petstore/python-flask/setup.py
+++ b/samples/server/petstore/python-flask/setup.py
@@ -1,5 +1,3 @@
-# coding: utf-8
-
 import sys
 from setuptools import setup, find_packages