              kwargs.pop('allow_blank', None)
  
          return field_cls, kwargs
  
      def build_relational_field(self, field_name, info, model):
          """
          Create fields for forward and reverse relationships.
          """
          relation_info = info.relations[field_name]
  
 
</s> remove         relation_info = info.relations[field_name]

        field_cls = self.serializer_related_class
        kwargs = get_relation_kwargs(field_name, relation_info)
 </s> add         field_class = self.serializer_related_class
        field_kwargs = get_relation_kwargs(field_name, relation_info) </s> remove     def build_nested_field(self, field_name, info, model, nested_depth):
 </s> add     def build_nested_field(self, field_name, relation_info, nested_depth): </s> remove         relation_info = info.relations[field_name]

 </s> add  </s> remove         return field_cls, kwargs
 </s> add         return field_class, field_kwargs </s> remove         return field_cls, kwargs
 </s> add         return field_class, field_kwargs
    def build_relational_field(self, field_name, relation_info):
              kwargs.pop('allow_blank', None)
  
          return field_cls, kwargs
  
    def build_relational_field(self, field_name, relation_info):
          """
          Create fields for forward and reverse relationships.
          """
          relation_info = info.relations[field_name]
  
keep keep keep keep replace keep keep keep keep keep
 Final bits of docs for ModelSerializer fields API 
rest_framework/serializers.py