vyspiansky

<?php
/**
 * The below functions take the single level array of items as an argument
 * and turn it into a multidimensional array structure (tree),
 * where each item has an array of sub-items.
 *
 * Each item should have at least an `id` and `parent_id`,
 * where the `parent_id` is `0` if it's top level.
 *
 * Source: http://goo.gl/p2GybZ