Wait for all connections to close. There are no side-effects here. 
        We just want to try and leave -after- everything has closed, in 
        general.

def __join_connections(self):
        """Wait for all connections to close. There are no side-effects here. 
        We just want to try and leave -after- everything has closed, in 
        general.
        """

        interval_s = nsq.config.client.CONNECTION_CLOSE_AUDIT_WAIT_S
        graceful_wait_s = nsq.config.client.CONNECTION_QUIT_CLOSE_TIMEOUT_S
        graceful = False

        while graceful_wait_s > 0:
            if not self.__connections:
                break

            connected_list = [c.is_connected for (n, c, g) in self.__connections]
            if any(connected_list) is False:
                graceful = True
                break

            # We need to give the greenlets periodic control, in order to finish 
            # up.

            gevent.sleep(interval_s)
            graceful_wait_s -= interval_s

        if graceful is False:
            connected_list = [c for (n, c, g) in self.__connections if c.is_connected]
            _logger.error("We were told to terminate, but not all "
                          "connections were stopped: [%s]", connected_list)