Take a list of strings and turn it into a nested associative array

nestify.php

<?php

function nestify($list, &$master) {

  if (empty($list)) {
    return $master;
  }

  $key = array_shift($list);

  if (empty($master[$key])) {
    $master[$key] = array();
  }

  nestify($list, $master[$key]);

}

$meta = array("region" => array("blah" => "duh"));
$list = ["region", "hero", "thing"];

nestify($list, $meta);

print_r($meta);

Here is this example code executed in a PHP sandbox: http://sandbox.onlinephpfunctions.com/code/b78695ef2300cd8c8648f75ea659dbd79d3dd15e