  import json
  
  from django.conf.urls.defaults import patterns, url
  from django.test import TestCase
  
  from djangorestframework.response import Response, ImmediateResponse
  from djangorestframework.mixins import ResponseMixin
 
</s> remove from djangorestframework.response import Response, ErrorResponse
 </s> add from djangorestframework.response import Response, ImmediateResponse </s> remove from djangorestframework.response import Response, ErrorResponse
 </s> add from djangorestframework.response import Response, ImmediateResponse </s> remove from djangorestframework.response import Response, ErrorResponse
 </s> add from djangorestframework.response import Response, ImmediateResponse </s> remove from djangorestframework.response import ErrorResponse
 </s> add from djangorestframework.response import ImmediateResponse </s> remove from djangorestframework.response import ErrorResponse
 </s> add from djangorestframework.response import ImmediateResponse
import unittest
  import json
import unittest
  
  from django.conf.urls.defaults import patterns, url
  from django.test import TestCase
  
  from djangorestframework.response import Response, ImmediateResponse
  from djangorestframework.mixins import ResponseMixin
add keep keep keep keep keep keep
 cleaned a bit Response/ResponseMixin code, added some documentation + renamed ErrorResponse to ImmediateResponse 
djangorestframework/tests/response.py