3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = array(); $a[] = array('1',null); $a[] = array('1','2'); $a[] = array('2',null); $a[] = array('2','2'); $a[] = array('1',null); $a[] = array('2','2'); print_r(array_unique($a));

preferences:
33.43 ms | 402 KiB | 5 Q