      def __call__(self, value):
          serializer = self.serializer_field
  
          # Determine the existing instance, if this is an update operation.
          instance = getattr(serializer, 'instance', None)
  
          # Ensure uniqueness.
          filter_kwargs = dict([
              (field_name, value[field_name]) for field_name in self.fields
          ])
 
</s> remove     def __call__(self, value):
        serializer = self.serializer_field

 </s> add     def set_context(self, serializer): </s> remove             (field_name, value[field_name]) for field_name in self.fields
 </s> add             (field_name, attrs[field_name]) for field_name in self.fields </s> remove     def __call__(self, value):
        field = self.serializer_field

        # Determine the model field name that the serializer field corresponds to.
        field_name = field.source_attrs[0] if field.source_attrs else field.field_name

 </s> add     def set_context(self, serializer_field):
        # Determine the underlying model field name. This may not be the
        # same as the serializer field name if `source=<>` is set.
        self.field_name = serializer_field.source_attrs[0]
        self.instance = getattr(serializer, 'instance', None)
      def __call__(self, value):
          serializer = self.serializer_field
  
          # Determine the existing instance, if this is an update operation.
        self.instance = getattr(serializer, 'instance', None)
  
          # Ensure uniqueness.
          filter_kwargs = dict([
              (field_name, value[field_name]) for field_name in self.fields
          ])
keep keep keep keep replace keep keep keep keep keep
 First pass at unique_for_date, unique_for_month, unique_for_year 
rest_framework/validators.py