public function createServer(int $port = 80) : Server
    {
        $listenIPv4 = new Directive('listen', [new Param($port)]);
        $listenIPv6 = new Directive('listen', [new Param("[::]:{$port}"), new Param('default'), new Param('ipv6only=on')]);

        return new Server([$listenIPv4, $listenIPv6]);
    }