Either the well was very deep, or she fell very slowly, for she
had plenty of time as she went down to look about her and to
wonder what was going to happen next.  First, she tried to look
down and make out what she was coming to, but it was too dark to
see anything; then she looked at the sides of the well, and
noticed that they were filled with cupboards and book-shelves;
here and there she saw maps and pictures hung upon pegs.  She

          return newValue;
        }
      }
      return oldValue;
    }

    /**
     * Refreshes the value associated with {@code key}, unless another thread is already doing so.
     * Returns the newly refreshed value associated with {@code key} if it was refreshed inline, or
     * {@code null} if another thread is performing the refresh or if an error occurs during
     * refresh.
     */

  Either the well was very deep, or she fell very slowly, for she
had plenty of time as she went down to look about her and to
wonder what was going to happen next.  First, she tried to look
down and make out what she was coming to, but it was too dark to
see anything; then she looked at the sides of the well, and
noticed that they were filled with cupboards and book-shelves;
here and there she saw maps and pictures hung upon pegs.  She

     *   <li>Return a {@code ClosingFuture}. To turn a {@link ListenableFuture} into a {@code
     *       ClosingFuture} call {@link #from(ListenableFuture)}.
     * </ul>
     *
     * <p>The same warnings about doing heavyweight operations within {@link
     * ClosingFuture#transformAsync(AsyncClosingFunction, Executor)} apply here.
     */
    public <V extends @Nullable Object> ClosingFuture<V> callAsync(

     *   <li>Return a {@code ClosingFuture}. To turn a {@link ListenableFuture} into a {@code
     *       ClosingFuture} call {@link #from(ListenableFuture)}.
     * </ul>
     *
     * <p>The same warnings about doing heavyweight operations within {@link
     * ClosingFuture#transformAsync(AsyncClosingFunction, Executor)} apply here.
     */
    public <V extends @Nullable Object> ClosingFuture<V> callAsync(

          return newValue;
        }
      }
      return oldValue;
    }

    /**
     * Refreshes the value associated with {@code key}, unless another thread is already doing so.
     * Returns the newly refreshed value associated with {@code key} if it was refreshed inline, or
     * {@code null} if another thread is performing the refresh or if an error occurs during
     * refresh.
     */