public function index($page = null)
    {
        $url = sprintf('buckets/%d/message_boards/%d/messages.json', $this->bucket, $this->parent);

        $messages = $this->client->get($url, [
            'query' => [
                'page' => $page,
            ],
        ]);

        return $this->indexResponse($messages, Message::class);
    }