Idempotent non-blocking connection attempt to the given node id.

def _maybe_connect(self, node_id):
        """Idempotent non-blocking connection attempt to the given node id."""
        with self._lock:
            conn = self._conns.get(node_id)

            if conn is None:
                broker = self.cluster.broker_metadata(node_id)
                assert broker, 'Broker id %s not in current metadata' % (node_id,)

                log.debug("Initiating connection to node %s at %s:%s",
                          node_id, broker.host, broker.port)
                host, port, afi = get_ip_port_afi(broker.host)
                cb = WeakMethod(self._conn_state_change)
                conn = BrokerConnection(host, broker.port, afi,
                                        state_change_callback=cb,
                                        node_id=node_id,
                                        **self.config)
                self._conns[node_id] = conn

            # Check if existing connection should be recreated because host/port changed
            elif self._should_recycle_connection(conn):
                self._conns.pop(node_id)
                return False

            elif conn.connected():
                return True

            conn.connect()
            return conn.connected()