public function sendStatus(int $status, string $protocol = '')
    {
        if (headers_sent()) {
            throw $this->c::issue('Headers already sent.');
        }
        if (!$protocol && !($protocol = $_SERVER['SERVER_PROTOCOL'] ?? '')) {
            $protocol = 'HTTP/1.1'; // Default fallback.
        }
        header($protocol.' '.$status.' '.$this->getStatusTitle($status), true, $status);
    }