public function notify(
        $message,
        $color = Client::COLOR_YELLOW,
        $alert = false,
        $format = Client::FORMAT_TEXT
    ) {
        $query = json_encode([
            'message' => $message,
            'color' => $color,
            'notify' => $alert,
            'format' => $format
        ]);

        $response = $this->client->post("/v2/room/{$this->room}/notification", $query);

        if ($response->getStatusCode() === 204) {
            return true;
        }

        //TODO: add proper exception.
        throw new \Exception($response->getBody(), $response->getStatusCode());
    }