I don't know why this is false

That is the Problem:

[05:56:03] [Server thread/CRITICAL]: ParseError: "syntax error, unexpected '{'" (EXCEPTION) in "plugins/teleporter/src/fixed/Main" at line 13

And thats my Code:

<?php

namespace Server;

use pocketmine\plugin\PluginBase;
use pocketmine\event\Listener;
use pocketmine\command\CommandSender;
use pocketmine\command\Command;
use pocketmine\Player;
use pocketmine\plugin\Plugin;
use jojoe77777\FormAPI\SimpleForm;

class Main extends Listener{

public function openHelpUI(){
$form = new SimpleForm(function(Player $player, int $data = null) {});
$form->addbutton("§3Citybuild");
}
public function onCommand(CommandSender $sender, string $commandLabel, array $args) {
switch ($args[0]) {
case "tpuicity":
$this->openHelpUI($sender, "Menu Opened");
}
}
}

 

Where is line 13?

 

class BuildFFA extends PluginBase implements Listener{
This is line 13

 

class BuildFFA extends PluginBase implements Listener{

 

remove }