pocketmine\command\Command::getUsage PHP Method

    public function getUsage()
    {
        return $this->usageMessage;
    }

 public function onCommand(CommandSender $sender, Command $command, $label, array $args)
 {
     if ($label === "transfer") {
         if (count($args) < 2 or count($args) > 3 or count($args) === 2 and !$sender instanceof Player) {
             $sender->sendMessage(new TranslationContainer("commands.generic.usage", [$command->getUsage()]));
             return true;
         }
         /** @var Player $target */
         $target = $sender;
         if (count($args) === 3) {
             $target = $sender->getServer()->getPlayer($args[0]);
             $address = $args[1];
             $port = (int) $args[2];
         } else {
             $address = $args[0];
             $port = (int) $args[1];
         }
         if ($target === null) {
             $sender->sendMessage(new TranslationContainer(TextFormat::RED . "%commands.generic.player.notFound"));
             return true;
         }
         $sender->sendMessage("Transferring player " . $target->getDisplayName() . " to {$address}:{$port}");
         if (!$this->transferPlayer($target, $address, $port)) {
             $sender->sendMessage(TextFormat::RED . "An error occurred during the transfer");
         }
         return true;
     }
     return false;
 }