Recursive Key Exists

<?php
function recursiveKeyExists($search = '', array $array = array())
{
    foreach ($array as $key => $value) {
        if (is_array($value)) {
            $found = recursiveKeyExists($search, $value);
            if ($found) {
                return true;
            }
        }
        if ($key === $search) {
            return true;
        }
    }
    return false;
}