Service at most `limit` number of messages from the view_changer's outBox.

        :return: the number of messages successfully serviced.

def serviceViewChangerOutBox(self, limit: int = None) -> int:
        """
        Service at most `limit` number of messages from the view_changer's outBox.

        :return: the number of messages successfully serviced.
        """
        msgCount = 0
        while self.view_changer.outBox and (not limit or msgCount < limit):
            msgCount += 1
            msg = self.view_changer.outBox.popleft()
            if isinstance(msg, (InstanceChange, ViewChangeDone)):
                self.send(msg)
            else:
                logger.error("Received msg {} and don't know how to handle it".
                             format(msg))
        return msgCount