public static function is_ajax($is_phery = false)
    {
        switch ($is_phery) {
            case true:
                return (bool)(!empty($_SERVER['HTTP_X_REQUESTED_WITH']) &&
                    strcasecmp($_SERVER['HTTP_X_REQUESTED_WITH'], 'XMLHttpRequest') === 0 &&
                    strtoupper($_SERVER['REQUEST_METHOD']) === 'POST' &&
                    !empty($_SERVER['HTTP_X_PHERY']));
            case false:
                return (bool)(!empty($_SERVER['HTTP_X_REQUESTED_WITH']) &&
                    strcasecmp($_SERVER['HTTP_X_REQUESTED_WITH'], 'XMLHttpRequest') === 0);
        }
        return false;
    }