docs: def match_serializers(self, serializers, default_media_type):
          """Choose serializer for a given request based on query arg or headers.
  
          Checks if query arg `format` (by default) is present and tries to match
          the serializer based on the arg value, by resolving the mimetype mapped
          to the arg value.
          Otherwise, chooses the serializer by retrieving the best quality
          `Accept` headers and matching its value (mimetype).
  
          :param serializers: Dictionary of serializers.
          :param default_media_type: The default media type.
          :returns: Best matching serializer based on `format` query arg first,
              then client `Accept` headers or None if no matching serializer.
          """
          return self._match_serializers_by_query_arg(serializers) or self.\
              _match_serializers_by_accept_headers(serializers,
                                                   default_media_type)