          return data
  
      def to_representation(self, value):
          if not value:
              return None
  
          if use_url:
 
</s> remove         if self.use_url:
 </s> add         if use_url: </s> remove         humanized_format = humanize_datetime.date_formats(self.input_formats)
 </s> add         humanized_format = humanize_datetime.date_formats(input_formats) </s> remove         if self.format is None:
 </s> add         if output_format is None: </s> remove         if self.format.lower() == ISO_8601:
 </s> add         if output_format.lower() == ISO_8601:
        use_url = getattr(self, 'use_url', api_settings.UPLOADED_FILES_USE_URL)

          return data
  
      def to_representation(self, value):
        use_url = getattr(self, 'use_url', api_settings.UPLOADED_FILES_USE_URL)

          if not value:
              return None
  
          if use_url:
keep keep add keep keep keep keep
 Access settings lazily, not at module import 
rest_framework/fields.py