  
      def save(self, **kwargs):
          validated_data = self.validated_data
          if kwargs:
              validated_data = dict(
                  list(validated_data.items()) +
 
</s>
        assert not hasattr(self, 'restore_object'), (
            'Serializer %s has old-style version 2 `.restore_object()` '
            'that is no longer compatible with REST framework 3. '
            'Use the new-style `.create()` and `.update()` methods instead.' %
            self.__class__.__name__
        )

  
      def save(self, **kwargs):
        assert not hasattr(self, 'restore_object'), (
            'Serializer %s has old-style version 2 `.restore_object()` '
            'that is no longer compatible with REST framework 3. '
            'Use the new-style `.create()` and `.update()` methods instead.' %
            self.__class__.__name__
        )

          validated_data = self.validated_data
          if kwargs:
              validated_data = dict(
                  list(validated_data.items()) +
keep add keep keep keep keep
 Stricter checking for failure cases.
rest_framework/serializers.py