diff --git a/modules/swagger-codegen/src/main/resources/python/model.mustache b/modules/swagger-codegen/src/main/resources/python/model.mustache
index 5668793b3f6..3febb23e698 100644
--- a/modules/swagger-codegen/src/main/resources/python/model.mustache
+++ b/modules/swagger-codegen/src/main/resources/python/model.mustache
@@ -4,11 +4,10 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 {{#imports}}{{#-first}}
 {{/-first}}
-{{import}}  # noqa: F401,E501
+# {{import}}  # noqa: F401,E501
 {{/imports}}
 
 
diff --git a/samples/client/petstore/python/.swagger-codegen/VERSION b/samples/client/petstore/python/.swagger-codegen/VERSION
index f9f7450d135..a6254504e40 100644
--- a/samples/client/petstore/python/.swagger-codegen/VERSION
+++ b/samples/client/petstore/python/.swagger-codegen/VERSION
@@ -1 +1 @@
-2.3.0-SNAPSHOT
\ No newline at end of file
+2.3.1
\ No newline at end of file
diff --git a/samples/client/petstore/python/petstore_api/models/additional_properties_class.py b/samples/client/petstore/python/petstore_api/models/additional_properties_class.py
index 03dbe975f1b..02c8b761111 100644
--- a/samples/client/petstore/python/petstore_api/models/additional_properties_class.py
+++ b/samples/client/petstore/python/petstore_api/models/additional_properties_class.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/animal.py b/samples/client/petstore/python/petstore_api/models/animal.py
index 390ac83905e..16f5ae45e91 100644
--- a/samples/client/petstore/python/petstore_api/models/animal.py
+++ b/samples/client/petstore/python/petstore_api/models/animal.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/animal_farm.py b/samples/client/petstore/python/petstore_api/models/animal_farm.py
index 6371257286e..29f15c06b69 100644
--- a/samples/client/petstore/python/petstore_api/models/animal_farm.py
+++ b/samples/client/petstore/python/petstore_api/models/animal_farm.py
@@ -13,10 +13,9 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
-from petstore_api.models.animal import Animal  # noqa: F401,E501
+# from petstore_api.models.animal import Animal  # noqa: F401,E501
 
 
 class AnimalFarm(object):
diff --git a/samples/client/petstore/python/petstore_api/models/api_response.py b/samples/client/petstore/python/petstore_api/models/api_response.py
index 45c4831bb10..5eb15544ccf 100644
--- a/samples/client/petstore/python/petstore_api/models/api_response.py
+++ b/samples/client/petstore/python/petstore_api/models/api_response.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/array_of_array_of_number_only.py b/samples/client/petstore/python/petstore_api/models/array_of_array_of_number_only.py
index c6b363f19d8..de7402a91d5 100644
--- a/samples/client/petstore/python/petstore_api/models/array_of_array_of_number_only.py
+++ b/samples/client/petstore/python/petstore_api/models/array_of_array_of_number_only.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/array_of_number_only.py b/samples/client/petstore/python/petstore_api/models/array_of_number_only.py
index 240362696cd..bc9c30ff0c4 100644
--- a/samples/client/petstore/python/petstore_api/models/array_of_number_only.py
+++ b/samples/client/petstore/python/petstore_api/models/array_of_number_only.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/array_test.py b/samples/client/petstore/python/petstore_api/models/array_test.py
index c5cd6bfe159..ce996c16d60 100644
--- a/samples/client/petstore/python/petstore_api/models/array_test.py
+++ b/samples/client/petstore/python/petstore_api/models/array_test.py
@@ -13,10 +13,9 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
-from petstore_api.models.read_only_first import ReadOnlyFirst  # noqa: F401,E501
+# from petstore_api.models.read_only_first import ReadOnlyFirst  # noqa: F401,E501
 
 
 class ArrayTest(object):
diff --git a/samples/client/petstore/python/petstore_api/models/capitalization.py b/samples/client/petstore/python/petstore_api/models/capitalization.py
index 309642bdeff..6b981951435 100644
--- a/samples/client/petstore/python/petstore_api/models/capitalization.py
+++ b/samples/client/petstore/python/petstore_api/models/capitalization.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/cat.py b/samples/client/petstore/python/petstore_api/models/cat.py
index 526d3e2aaf5..1ff3c781470 100644
--- a/samples/client/petstore/python/petstore_api/models/cat.py
+++ b/samples/client/petstore/python/petstore_api/models/cat.py
@@ -13,10 +13,9 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
-from petstore_api.models.animal import Animal  # noqa: F401,E501
+# from petstore_api.models.animal import Animal  # noqa: F401,E501
 
 
 class Cat(object):
diff --git a/samples/client/petstore/python/petstore_api/models/category.py b/samples/client/petstore/python/petstore_api/models/category.py
index 02d393af888..2785b38e859 100644
--- a/samples/client/petstore/python/petstore_api/models/category.py
+++ b/samples/client/petstore/python/petstore_api/models/category.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/class_model.py b/samples/client/petstore/python/petstore_api/models/class_model.py
index 4bcb19b8dc2..baa2e1ea54f 100644
--- a/samples/client/petstore/python/petstore_api/models/class_model.py
+++ b/samples/client/petstore/python/petstore_api/models/class_model.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/client.py b/samples/client/petstore/python/petstore_api/models/client.py
index e267fed6d8c..05d362b447c 100644
--- a/samples/client/petstore/python/petstore_api/models/client.py
+++ b/samples/client/petstore/python/petstore_api/models/client.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/dog.py b/samples/client/petstore/python/petstore_api/models/dog.py
index 34aac6aaad4..b1bf27ab4fa 100644
--- a/samples/client/petstore/python/petstore_api/models/dog.py
+++ b/samples/client/petstore/python/petstore_api/models/dog.py
@@ -13,10 +13,9 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
-from petstore_api.models.animal import Animal  # noqa: F401,E501
+# from petstore_api.models.animal import Animal  # noqa: F401,E501
 
 
 class Dog(object):
diff --git a/samples/client/petstore/python/petstore_api/models/enum_arrays.py b/samples/client/petstore/python/petstore_api/models/enum_arrays.py
index d02be298d2f..4a7a758466c 100644
--- a/samples/client/petstore/python/petstore_api/models/enum_arrays.py
+++ b/samples/client/petstore/python/petstore_api/models/enum_arrays.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/enum_class.py b/samples/client/petstore/python/petstore_api/models/enum_class.py
index e4721545e83..231fad1c68a 100644
--- a/samples/client/petstore/python/petstore_api/models/enum_class.py
+++ b/samples/client/petstore/python/petstore_api/models/enum_class.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/enum_test.py b/samples/client/petstore/python/petstore_api/models/enum_test.py
index 1bb234764ab..3606abd57d0 100644
--- a/samples/client/petstore/python/petstore_api/models/enum_test.py
+++ b/samples/client/petstore/python/petstore_api/models/enum_test.py
@@ -13,10 +13,9 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
-from petstore_api.models.outer_enum import OuterEnum  # noqa: F401,E501
+# from petstore_api.models.outer_enum import OuterEnum  # noqa: F401,E501
 
 
 class EnumTest(object):
diff --git a/samples/client/petstore/python/petstore_api/models/format_test.py b/samples/client/petstore/python/petstore_api/models/format_test.py
index 7974d732fda..b4984fa3e2d 100644
--- a/samples/client/petstore/python/petstore_api/models/format_test.py
+++ b/samples/client/petstore/python/petstore_api/models/format_test.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/has_only_read_only.py b/samples/client/petstore/python/petstore_api/models/has_only_read_only.py
index 3c93eb30996..bf3cda26486 100644
--- a/samples/client/petstore/python/petstore_api/models/has_only_read_only.py
+++ b/samples/client/petstore/python/petstore_api/models/has_only_read_only.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/list.py b/samples/client/petstore/python/petstore_api/models/list.py
index fbe30e6d01e..d9faf90af46 100644
--- a/samples/client/petstore/python/petstore_api/models/list.py
+++ b/samples/client/petstore/python/petstore_api/models/list.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/map_test.py b/samples/client/petstore/python/petstore_api/models/map_test.py
index 374c0661ba5..a72f0917ba1 100644
--- a/samples/client/petstore/python/petstore_api/models/map_test.py
+++ b/samples/client/petstore/python/petstore_api/models/map_test.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/mixed_properties_and_additional_properties_class.py b/samples/client/petstore/python/petstore_api/models/mixed_properties_and_additional_properties_class.py
index dba1f261352..61abb59f6f0 100644
--- a/samples/client/petstore/python/petstore_api/models/mixed_properties_and_additional_properties_class.py
+++ b/samples/client/petstore/python/petstore_api/models/mixed_properties_and_additional_properties_class.py
@@ -13,10 +13,9 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
-from petstore_api.models.animal import Animal  # noqa: F401,E501
+# from petstore_api.models.animal import Animal  # noqa: F401,E501
 
 
 class MixedPropertiesAndAdditionalPropertiesClass(object):
diff --git a/samples/client/petstore/python/petstore_api/models/model_200_response.py b/samples/client/petstore/python/petstore_api/models/model_200_response.py
index 60f9c96a676..131944cbae7 100644
--- a/samples/client/petstore/python/petstore_api/models/model_200_response.py
+++ b/samples/client/petstore/python/petstore_api/models/model_200_response.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/model_return.py b/samples/client/petstore/python/petstore_api/models/model_return.py
index c9d8b5682aa..6bbd42e7586 100644
--- a/samples/client/petstore/python/petstore_api/models/model_return.py
+++ b/samples/client/petstore/python/petstore_api/models/model_return.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/name.py b/samples/client/petstore/python/petstore_api/models/name.py
index cbfbddeb1ab..56e8fe0bd76 100644
--- a/samples/client/petstore/python/petstore_api/models/name.py
+++ b/samples/client/petstore/python/petstore_api/models/name.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/number_only.py b/samples/client/petstore/python/petstore_api/models/number_only.py
index b96321109b9..bae6475ff12 100644
--- a/samples/client/petstore/python/petstore_api/models/number_only.py
+++ b/samples/client/petstore/python/petstore_api/models/number_only.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/order.py b/samples/client/petstore/python/petstore_api/models/order.py
index 6636542e941..d487b5c4696 100644
--- a/samples/client/petstore/python/petstore_api/models/order.py
+++ b/samples/client/petstore/python/petstore_api/models/order.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/outer_boolean.py b/samples/client/petstore/python/petstore_api/models/outer_boolean.py
index 9b3aebd3608..ffa88d4dadd 100644
--- a/samples/client/petstore/python/petstore_api/models/outer_boolean.py
+++ b/samples/client/petstore/python/petstore_api/models/outer_boolean.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/outer_composite.py b/samples/client/petstore/python/petstore_api/models/outer_composite.py
index 19775255e4e..b569085d773 100644
--- a/samples/client/petstore/python/petstore_api/models/outer_composite.py
+++ b/samples/client/petstore/python/petstore_api/models/outer_composite.py
@@ -13,12 +13,11 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
-from petstore_api.models.outer_boolean import OuterBoolean  # noqa: F401,E501
-from petstore_api.models.outer_number import OuterNumber  # noqa: F401,E501
-from petstore_api.models.outer_string import OuterString  # noqa: F401,E501
+# from petstore_api.models.outer_boolean import OuterBoolean  # noqa: F401,E501
+# from petstore_api.models.outer_number import OuterNumber  # noqa: F401,E501
+# from petstore_api.models.outer_string import OuterString  # noqa: F401,E501
 
 
 class OuterComposite(object):
diff --git a/samples/client/petstore/python/petstore_api/models/outer_enum.py b/samples/client/petstore/python/petstore_api/models/outer_enum.py
index 5ee1e49a587..e46f7c763fe 100644
--- a/samples/client/petstore/python/petstore_api/models/outer_enum.py
+++ b/samples/client/petstore/python/petstore_api/models/outer_enum.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/outer_number.py b/samples/client/petstore/python/petstore_api/models/outer_number.py
index a35587be65e..6b49df9e526 100644
--- a/samples/client/petstore/python/petstore_api/models/outer_number.py
+++ b/samples/client/petstore/python/petstore_api/models/outer_number.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/outer_string.py b/samples/client/petstore/python/petstore_api/models/outer_string.py
index 736edacd1bc..0580429d851 100644
--- a/samples/client/petstore/python/petstore_api/models/outer_string.py
+++ b/samples/client/petstore/python/petstore_api/models/outer_string.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/pet.py b/samples/client/petstore/python/petstore_api/models/pet.py
index 81b2bb617f9..985282d3ab0 100644
--- a/samples/client/petstore/python/petstore_api/models/pet.py
+++ b/samples/client/petstore/python/petstore_api/models/pet.py
@@ -13,11 +13,10 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
-from petstore_api.models.category import Category  # noqa: F401,E501
-from petstore_api.models.tag import Tag  # noqa: F401,E501
+# from petstore_api.models.category import Category  # noqa: F401,E501
+# from petstore_api.models.tag import Tag  # noqa: F401,E501
 
 
 class Pet(object):
diff --git a/samples/client/petstore/python/petstore_api/models/read_only_first.py b/samples/client/petstore/python/petstore_api/models/read_only_first.py
index 106463077e8..a6f0d7f05ac 100644
--- a/samples/client/petstore/python/petstore_api/models/read_only_first.py
+++ b/samples/client/petstore/python/petstore_api/models/read_only_first.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/special_model_name.py b/samples/client/petstore/python/petstore_api/models/special_model_name.py
index a31b8db66e2..5253e86112b 100644
--- a/samples/client/petstore/python/petstore_api/models/special_model_name.py
+++ b/samples/client/petstore/python/petstore_api/models/special_model_name.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/tag.py b/samples/client/petstore/python/petstore_api/models/tag.py
index b486a672b88..93be258d5d7 100644
--- a/samples/client/petstore/python/petstore_api/models/tag.py
+++ b/samples/client/petstore/python/petstore_api/models/tag.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six
 
 
diff --git a/samples/client/petstore/python/petstore_api/models/user.py b/samples/client/petstore/python/petstore_api/models/user.py
index c9fe0072a9c..d69ae40fa19 100644
--- a/samples/client/petstore/python/petstore_api/models/user.py
+++ b/samples/client/petstore/python/petstore_api/models/user.py
@@ -13,7 +13,6 @@
 
 import pprint
 import re  # noqa: F401
-
 import six