  
          if many and instance is not None and not hasattr(instance, '__iter__'):
              raise ValueError('instance should be a queryset or other iterable with many=True')
  
          if allow_delete and not many:
              raise ValueError('allow_delete should only be used for bulk updates, but you have not set many=True')
  
      #####
      # Methods to determine which fields to use when (de)serializing objects.
  
      def get_default_fields(self):
 
</s> remove         if self.allow_delete and self._deleted:
 </s> add         if self.allow_add_remove and self._deleted:
        if allow_add_remove and not many:
            raise ValueError('allow_add_remove should only be used for bulk updates, but you have not set many=True')
  
          if many and instance is not None and not hasattr(instance, '__iter__'):
              raise ValueError('instance should be a queryset or other iterable with many=True')
  
        if allow_add_remove and not many:
            raise ValueError('allow_add_remove should only be used for bulk updates, but you have not set many=True')
        if allow_add_remove and not many:
            raise ValueError('allow_add_remove should only be used for bulk updates, but you have not set many=True')
  
      #####
      # Methods to determine which fields to use when (de)serializing objects.
  
      def get_default_fields(self):
keep keep keep keep replace replace keep keep keep keep keep
 one-many writable nested modelserializer support 
rest_framework/serializers.py