[Python] AttributeError: module 'typing' has no attribute 'Type' in python 3.5.1

Description

In python 3.5.1, type python -m swagger_server will get the following error:
File "/swagger-codegen/samples/server/petstore/flaskConnexion/swagger_server/models/base_model_.py", line 21, in Model
def from_dict(cls: typing.Type[T], dikt) -> T:
AttributeError: module 'typing' has no attribute 'Type'

Swagger-codegen version

2.3.0

Suggest a fix/enhancement

1. edit swagger_server/models/base_model_.py
2. add from typing import TypeVar, Generic after import typing
3. replace the 22nd line as below

def from_dict(cls: typing.Type[T], dikt) -> T:
def from_dict(cls: typing.Generic[T], dikt) -> T:

4. type python -m swagger_server to start the service and you would see:
   * Running on http://0.0.0.0:8080/ (Press CTRL+C to quit)

Start with swagger_server/models/base_model_.py, especially the from_dict annotation around line 22, and reproduce the failure with python -m swagger_server under Python 3.5.1. Verify the compatibility change against the generated Flask service; done means the service starts and reports that it is running on port 8080.