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run code in 300+ PHP versions simultaneously
<?php class Check { private static $instance; public function getInstance($name = null) { if (isset(self::$instance)) { return self::$instance; } self::$instance = $name; return self::$instance; } } $a = new Check; var_dump($a->getInstance('a')); $b = new Check; var_dump($b->getInstance('b')); var_dump($a->getInstance());

preferences:
28.37 ms | 402 KiB | 5 Q