protected function buildReply($to, $from, $message)
    {
        $base = [
            'ToUserName'   => $to,
            'FromUserName' => $from,
            'CreateTime'   => time(),
            'MsgType'      => is_array($message) ? current($message)->getType() : $message->getType(),
        ];

        $transformer = new Transformer();

        return XML::build(array_merge($base, $transformer->transform($message)));
    }