if (!wasCancelled) {
        return new Failure(
            new IllegalArgumentException(
                "get() threw CancellationException, despite reporting isCancelled() == false: "
                    + future,
                cancellation));
      }
      return new Cancellation(false, cancellation);
    } catch (Exception | Error t) { // sneaky checked exception
      return new Failure(t);
    }
  }

  /**