public function enable($name, $ttl = NULL, &$created = FALSE) {
    $headers = array();
    if (!empty($ttl)) {
      $headers['X-TTL'] = (int) $ttl;
    }
    $res = $this->modifyContainer($name, 'PUT', $headers);
    $created = $res->status() == 201;

    $url = $res->header('X-Cdn-Uri', 'UNKNOWN');
    return $url;
  }