*
 * // later
 * try { // get() will throw if the operation failed or was cancelled.
 *   UserName userName = userNameValueAndCloser.get();
 *   // do something with userName
 * } finally {
 *   userNameValueAndCloser.closeAsync();
 * }
 * }</pre>
 *
 * In this example, when {@code userNameValueAndCloser.closeAsync()} is called, the transaction and

 *
 * // later
 * try { // get() will throw if the operation failed or was cancelled.
 *   UserName userName = userNameValueAndCloser.get();
 *   // do something with userName
 * } finally {
 *   userNameValueAndCloser.closeAsync();
 * }
 * }</pre>
 *
 * In this example, when {@code userNameValueAndCloser.closeAsync()} is called, the transaction and