- var_dump: documentation ( source)
- array_intersect: documentation ( source)
- array_merge: documentation ( source)
<?php
$one = [3 => 'en.yml'];
$two = [3 => 'de.yml'];
var_dump(array_merge($one, $two));
var_dump(array_merge($two, $one));
var_dump(array_intersect($one, $two));