public function start($deviceUUID, array $options = array())
  {
    // @throws InvalidArgumentException
    $this->checkArgument($deviceUUID, 'deviceUUID');

    list($code, $session) = $this->httpClient->post('/sync/start', null, array_merge($options, ['headers' => $this->buildHeaders($deviceUUID)]));

    if ($code == 204) return null;
    return $session;
  }