docs: def get_default(self):
      """
      Return the default value of the field. Returns either #default, the return
      value of #default_factory or raises a #RuntimeError if the field has no
      default value.
      """
  
      if self.default is not NotImplemented:
        return self.default
      elif self.default_factory is not None:
        return self.default_factory()
      else:
        raise RuntimeError('{0!r} has no default value'.format(self.full_name))