public function httpCode($http_code = 200, $protocol = 'HTTP/1.1')
    {
        $http_code = intval($http_code);
        $status_str = HttpHelper::get_status_code_message($http_code);
        if ($status_str) {
            header(implode(' ', [$protocol, $http_code, $status_str]));
        }
    }