<?php
/* https://forum.nette.org/cs/35218-muze-checkboxlist-vracet-associativni-pole-misto-indexoveho#p220072 */

0 => 'po'
1 => 'st'
2 => 'ct'


po => true
ut => false
st => true
ct => true
pa => false


array_walk($arr, fn(&$item, $key, $values) => $item = in_array($key, $values), $values);