  from djangorestframework.compat import RequestFactory
  from django.contrib.auth.models import Group, User
  from djangorestframework.mixins import CreateModelMixin, PaginatorMixin, ReadModelMixin
  from djangorestframework.resources import ModelResource
  from djangorestframework.response import Response, ErrorResponse
  from djangorestframework.tests.models import CustomUser
  from djangorestframework.tests.testcases import TestModelsTestCase
  from djangorestframework.views import View
  
  
 
</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
from djangorestframework.response import Response, ImmediateResponse
  from djangorestframework.compat import RequestFactory
  from django.contrib.auth.models import Group, User
  from djangorestframework.mixins import CreateModelMixin, PaginatorMixin, ReadModelMixin
  from djangorestframework.resources import ModelResource
from djangorestframework.response import Response, ImmediateResponse
  from djangorestframework.tests.models import CustomUser
  from djangorestframework.tests.testcases import TestModelsTestCase
  from djangorestframework.views import View
  
  
keep keep keep keep replace keep keep keep keep keep
 cleaned a bit Response/ResponseMixin code, added some documentation + renamed ErrorResponse to ImmediateResponse 
djangorestframework/tests/mixins.py