Change reserved word handling in python client.

* First, remove the beginning underscores.
* Then, append underscore if the var is reserved word or number.

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PythonClientCodegen.java

@@ -119,7 +119,7 @@ public class PythonClientCodegen extends DefaultCodegen implements CodegenConfig
 
     @Override
     public String escapeReservedWord(String name) {
-        return name + "_";
+        return "_" + name;
     }
 
     @Override
@@ -179,14 +179,14 @@ public class PythonClientCodegen extends DefaultCodegen implements CodegenConfig
         // petId => pet_id
         name = underscore(dropDots(name));
 
+        // remove leading underscore
+        name = name.replaceAll("^_*", "");
+
         // for reserved word or word starting with number, append _
         if (reservedWords.contains(name) || name.matches("^\\d.*")) {
             name = escapeReservedWord(name);
         }
 
-        // remove leading underscore
-        name = name.replaceAll("^_*", "");
-
         return name;
     }