public static function listing($items, $glue = ' &amp; ', $sep = ', ') {
        if (is_array($items)) {
            $lastItem = array_pop($items);

            if (count($items) === 0) {
                return $lastItem;
            }

            $items = implode($sep, $items);
            $items = $items . $glue . $lastItem;
        }

        return $items;
    }