Service `limit` number of received messages in this stack.

        :param limit: the maximum number of messages to be processed. If None,
        processes all of the messages in rxMsgs.
        :return: the number of messages processed.

async def service(self, limit=None, quota: Optional[Quota] = None) -> int:
        """
        Service `limit` number of received messages in this stack.

        :param limit: the maximum number of messages to be processed. If None,
        processes all of the messages in rxMsgs.
        :return: the number of messages processed.
        """
        if self.listener:
            await self._serviceStack(self.age, quota)
        else:
            logger.info("{} is stopped".format(self))

        r = len(self.rxMsgs)
        if r > 0:
            pracLimit = limit if limit else sys.maxsize
            return self.processReceived(pracLimit)
        return 0