public static function toUser(&$error)
    {
        $error_int = self::toInteger($error);
        switch($error_int) {
            case E_ERROR:
                $error = E_USER_ERROR;
                break;
            case E_WARNING:
                $error = E_USER_WARNING;
                break;
            case E_NOTICE:
                $error = E_USER_NOTICE;
                break;
            case E_DEPRECATED:
                $error = E_USER_DEPRECATED;
                break;
        }
        
        return self::isTrueUser($error);
    }