code: def _get_classes_to_inspect(self):
          
          return tuple(filter(lambda c:
                        SerializableMixIn._get_version(c, require=False) or
                        (SerializableMixIn._get_serialize_fields(c) or
                         SerializableMixIn._get_interpolation_map(c)),
                        self.__class__.__mro__))
docs: gets classes self derives from which
           1. have custom fields: __serialize_fields
           2. provide a modifications map