`Exactly so,' said the Hatter:  `as the things get used up.'

  `But what happens when you come to the beginning again?' Alice
ventured to ask.

  `Suppose we change the subject,' the March Hare interrupted,
yawning.  `I'm getting tired of this.  I vote the young lady
tells us a story.'

  `I'm afraid I don't know one,' said Alice, rather alarmed at
the proposal.

   * specified {@link MoreExecutors#directExecutor()}, those objects will be closed synchronously.
   *
   * @param mayInterruptIfRunning {@code true} if the thread executing this task should be
   *     interrupted; otherwise, in-progress tasks are allowed to complete, but the step will be
   *     cancelled regardless
   * @return {@code false} if the step could not be cancelled, typically because it has already