pocketmine\event\player\PlayerItemHeldEvent::getInventorySlot PHP Method

    public function getInventorySlot()
    {
        return $this->inventorySlot;
    }

 public function h_onItemHeld(PlayerItemHeldEvent $event)
 {
     switch ($this->getInventorySession()) {
         case self::INV_CHOOSE_GAME:
             $event->setCancelled();
             $slot = $event->getInventorySlot();
             $gameId = $slot | self::SES_STATE_GAME;
             if ($gameId === $this->session) {
                 $this->tell("You are already here!");
                 return;
             }
             $this->setInventorySession(self::INV_NORMAL_ACCESS);
             $game = $this->getGame();
             if ($game instanceof Game) {
                 $game->onQuit($this, false);
                 $this->unsubscribeFromChannel($game->getDefaultChatChannel());
             }
             $this->getPlayer()->getInventory()->clearAll();
             if ($gameId === self::SESSION_GAME_HUB) {
                 $this->switchSession(self::SESSION_GAME_HUB);
             } else {
                 $game = $this->main->getGame($gameId);
                 if (!$game instanceof Game) {
                     return;
                 }
                 if (!$this->joinGame($game)) {
                     $this->tell("This game is not available!");
                     $this->setInventorySession(self::INV_CHOOSE_GAME);
                 }
             }
             break;
     }
 }