docs: def maybe_convert_values(self,
                               identifier: Identifier,
                               data: Dict[str, Any],
                               ) -> Dict[str, Any]:
          """
          Takes a dictionary of raw values for a specific identifier, as parsed
          from the YAML file, and depending upon the type of db column the data
          is meant for, decides what to do with the value (eg leave it alone,
          convert a string to a date/time instance, or convert identifiers to
          model instances by calling :meth:`self.loader.convert_identifiers`)
  
          :param identifier: An object with :attr:`class_name` and :attr:`key`
                             attributes
          :param data: A dictionary keyed by column name, with values being the
                       raw values as parsed from the YAML
          :return: A dictionary keyed by column name, with values being the
                   converted values meant to be set on the model instance
          """
          raise NotImplementedError