def __on_publish(self, client, userdata, mid):
        # pylint: disable=W0613
        """
        A message has been published by a server

        :param client: Client that received the message
        :param userdata: User data (unused)
        :param mid: Message ID
        """
        try:
            self.__in_flight[mid].set()
        except KeyError:
            pass
A message has been published by a server

        :param client: Client that received the message
        :param userdata: User data (unused)
        :param mid: Message ID