How can I get the amount of players in a world?

I'm trying to check how many players are in a world. Very stumped rn.

http://php.net/manual/en/function.count.php

PHP:

count($this->getServer()->getLevelByName("World")->getPlayers());

This has been posted soo many time's no one bothers to search anymore: https://www.google.ca/search?q=site%3Apocketmine.net+get+players+in+a+world&

And its an easy question

Basically, instead of the link @basprohop supplied, just cut the middleman "GOOGLE" and use this link. https://forums.pocketmine.net/threads/get-player-in-the-world.8510/

This is my Methode to count the Players ;P

PHP:

$playercount = count($this->getServer()->getOnlinePlayers());