}

  /**
   * Starts a {@link ClosingFuture} pipeline by submitting a callable block to an executor.
   *
   * @throws java.util.concurrent.RejectedExecutionException if the task cannot be scheduled for
   *     execution
   */
  public static <V extends @Nullable Object> ClosingFuture<V> submit(
      ClosingCallable<V> callable, Executor executor) {
    return new ClosingFuture<>(callable, executor);
  }