JAXL::add_cb PHP Method

    public function add_cb($ev, $cb, $priority = 1)
    {
        return $this->ev->add($ev, $cb, $priority);
    }

 /**
  * Handles disconnections
  */
 private function attachOnDisconnectListener()
 {
     $this->client->add_cb('on_disconnect', function () {
         $this->getContainer()->get('logger')->warn('Got disconnected from XMPP. Reconnecting.');
         $this->startClient();
     });
 }