How do I use hidePlayer?

Haaalp this is a life or death situation, how do I use hidePlayer()? xD

maybe looking into the very old versions of vanish plugins?

example:

PHP:

foreach($this->getServer()->getOnlinePlayers() as $p){
$player->hidePlayer($p);//player can't see anyone.
}

PHP:

$player1->hidePlayer($player2);
// This will hide $player2 from $player1
$player1->showPlayer($player2);
// This will show $player2 for $player1