  
  class RetrieveModelMixin(object):
      """
      Retrieve a model instance.
      Should be mixed in with `SingleObjectBaseView`.
      """
      def retrieve(self, request, *args, **kwargs):
          self.object = self.get_object()
          serializer = self.get_serializer(self.object)
          return Response(serializer.data)
 
</s> remove     Should be mixed in with any `BaseView`.
 </s> add     Should be mixed in with any `GenericAPIView`. </s> remove     Should be mixed in with `SingleObjectBaseView`.
 </s> add     Should be mixed in with `SingleObjectAPIView`. </s> remove     Should be mixed in with `SingleObjectBaseView`.
 </s> add     Should be mixed in with `SingleObjectAPIView`.
    Should be mixed in with `SingleObjectAPIView`.
  
  class RetrieveModelMixin(object):
      """
      Retrieve a model instance.
    Should be mixed in with `SingleObjectAPIView`.
      """
      def retrieve(self, request, *args, **kwargs):
          self.object = self.get_object()
          serializer = self.get_serializer(self.object)
          return Response(serializer.data)
keep keep keep keep replace keep keep keep keep keep
 Fix out of date docstrings. Closes #689. 
rest_framework/mixins.py