- array_walk: documentation ( source)
<?php
$array_1 = array('something1', something2);
$array_2 = array('something3', something4);
$array_3 = array();
$array_4 = array('something1', something2);
$list = array($array_1,$array_2,$array_3,$array_4);
array_walk($list,function(&$value, $key){
});