docs: def get_field_mro(cls, field_name):
      """Goes up the mro and looks for the specified field."""
      res = set()
      if hasattr(cls, '__mro__'):
          for _class in inspect.getmro(cls):
              values_ = getattr(_class, field_name, None)
              if values_ is not None:
                  res = res.union(set(make_list(values_)))
      return res