          unless they exist in the `rename` dict.
          """
          return self.rename.get(smart_str(key), smart_str(key))
  
      def serialize_val(self, key, obj):
          """
          Convert a model field or dict value into a serializable representation.
          """
          related_serializer = self.get_related_serializer(key)
  
 
</s> remove         related_serializer = self.get_related_serializer(key)
 </s> add         related_serializer = self.get_related_serializer(related_info) </s> remove     return [_field_to_tuple(field)[0] for field in fields or ()]


def _fields_to_dict(fields):
    """
    Return a `dict` of field name -> None, or tuple of fields, or Serializer class
    """
    return dict([_field_to_tuple(field) for field in fields or ()])
 </s> add     return [_field_to_tuple(field) for field in fields or ()] </s> remove     Return a list of field names.
 </s> add     Return a list of field tuples. </s> remove         else:
            fields = _fields_to_list(self.fields)

 </s> add  </s> remove         """
        Return the set of field names/keys to use for a model instance/dict.
        """
 </s> add 
    def serialize_val(self, key, obj, related_info):
          unless they exist in the `rename` dict.
          """
          return self.rename.get(smart_str(key), smart_str(key))
  
    def serialize_val(self, key, obj, related_info):
          """
          Convert a model field or dict value into a serializable representation.
          """
          related_serializer = self.get_related_serializer(key)
  
keep keep keep keep replace keep keep keep keep keep
 Fix for #178.

Related serializers passed in via include now work as expected. 
djangorestframework/serializer.py