public static function getUrls()
    {
        $urls = [];

        foreach (static::$_crumbs as $crumb) {
            if (!empty($crumb['url'])) {
                $urls[] = $crumb['url'];
            } elseif (is_object($crumb)) {
                $urls[] = $crumb->url;
            }
        }

        return $urls;
    }