public function getQueryString() {
        // The variable $_SERVER['QUERY_STRING'] is set by the server and can differ from the transmitted query string.
        // It might hold additional parameters added by the server or it might be empty (e.g. on a mis-configured nginx).

        if (isset($_SERVER['QUERY_STRING']) && strlen($_SERVER['QUERY_STRING'])) {
            $query = $_SERVER['QUERY_STRING'];
        }
        else {
            $query = strRightFrom($_SERVER['REQUEST_URI'], '?');
        }
        return $query;
    }