teleport()

As I understand, to teleport player between worlds, I should use

PHP:

teleport(new position(coords here));

But what is the format of coords?
I have tried "x, y, z, level" and "level, x, y, z". It didn't work for me

I think (yes, i only think) it works like this

PHP:

$playerobject->teleport(new Vector3($x, $y, $z, $level)); 

Yes, but Vector3 needs to be Position

I advise you to do directly

PHP:

# Use if needed: $player=$issuer->username;
# Define $x, $y and $z (and $level if necessary)

# Use if needed: $this->api->console->run("tp $player w:$levelName");
$this->api->console->run("tp $player $x $y $z");

Saves lots of trouble messing with classes.

Yeah sorry sometimes my brain gets messy. But anyway there is such code:
https://github.com/PocketMine/PocketMine-MP/blob/master/src/Player.php#L2292

PHP:

function __toString(){
  if($this->username != ""){
    return $this->username;
  }
  return $this->clientID;
}

So it doesn't really matter.