code: def serializer_by_type_id(self, type_id):
          
          if type_id <= 0:
              indx = index_for_default_type(type_id)
              serializer = self._constant_type_ids.get(indx, None)
              if serializer is not None:
                  return serializer
          return self._id_dic.get(type_id, None)
docs: Find and return the serializer for the type-id
          :param type_id: type-id the serializer
          :return: the serializer