public function modifyChecks($check_ids, $parameters) {
    $this->ensureParameters(array(
      'check_ids' => $check_ids,
      'parameters' => $parameters,
    ), __METHOD__);
    $parameters['checkids'] = implode(',', $check_ids);
    $data = $this->request('PUT', 'checks', $parameters);
    return $data->message;
  }