public static function purify($dirtyHtml)
    {
        if (self::$htmlPurifier && self::$htmlPurifier instanceof \HTMLPurifier) {
            $purifier = self::$htmlPurifier;
        } else {
            $purifier = (self::$htmlPurifier = new \HTMLPurifier(\HTMLPurifier_Config::createDefault()));
        }
        return $purifier->purify($dirtyHtml);
    }