3v4l.org

run code in 500+ PHP versions simultaneously
<?php class Foo implements Iterator { public function current(): Foo { return $this; } public function key(): Foo { return $this; } public function next(): void {} public function rewind(): void {} public function valid(): bool { return true; } } foreach ( new Foo as $key => $value ) { var_dump($key, $value); break; }

preferences:
42.96 ms | 1479 KiB | 5 Q