Prevent "You dont have the permission for this command" on command?

How can I let non-ops execute OP commands, I want to make an own rank system, and no, I dont want to use PurePerms (because it is too common), so how can I do that?

Example:

PHP:

case "op":
if(isset(strtolower($args[0])){
if($rank == "guest"){
$this->getServer()->getPlayer($args[0])->setOp(true);


No, I mean how can I cancel that "You dont have the permission" message and let them execute the message

Use then PlayerCommandPreproccesEvent

But how? $event->setCancelled(false); in it?

PHP:

public function antiCmd(PlayerCommandPreproccesEvent $e){
$rank = // your getGroup() function, i dont know what fuctions are in PurePerms
$msg = $e->getMessage();
$p = $e->getPlayer();
if($msg == "/op"){
if($rank == "guest"){
$e->setCancelled();
$p->sendMessage("");
}
}
}


It's just example

I will try with $event->setCancelled(false);

No, it just setCancelled() or setCancelled(true);
When is false, him will show this permission message.

But he doesnt execute it then

This works:

PHP:

        public function onPlayerCommand(PlayerCommandPreprocessEvent $event){
            $message = $event->getMessage();
            if($message{0} === "/"){
                $event->setCancelled(true);
                $command = substr($message, 1);
                $args = explode(" ", $command);
                if($args[0] === "mycommand"){
                    $this->plugin->getServer()->dispatchCommand($event->getPlayer(), $command);
                }
            }
        }

Code is not mine but PocketMine Teams