          }
          return self._default_view_name % format_kwargs
  
      def get_pk_field(self, model_field):
          return None
  
      def get_related_field(self, model_field, to_many):
          """
          Creates a default instance of a flat relational field.
          """
 
</s> remove     def get_nested_field(self, model_field):
 </s> add     def get_nested_field(self, model_field, rel=None): </s> remove                 model = model_field.rel.to
 </s> add                 model = model_class </s> remove     def get_related_field(self, model_field, to_many=False):
 </s> add     def get_related_field(self, model_field, rel=None, to_many=False):
        if self.opts.fields and model_field.name in self.opts.fields:
            return self.get_field(model_field)
          }
          return self._default_view_name % format_kwargs
  
      def get_pk_field(self, model_field):
        if self.opts.fields and model_field.name in self.opts.fields:
            return self.get_field(model_field)
  
      def get_related_field(self, model_field, to_many):
          """
          Creates a default instance of a flat relational field.
          """
keep keep keep keep replace keep keep keep keep keep
 First pass on automatically including reverse relationship 
rest_framework/serializers.py