code: def __notify(self):
          
          if self.__callback is not None:
              try:
                  self.__callback(
                      self._done_event.data,
                      self._done_event.exception,
                      self.__extra,
                  )
              except Exception as ex:
                  self._logger.exception("Error calling back method: %s", ex)
docs: Notify the given callback about the result of the execution