*     operation is done
   */
  public void finishToValueAndCloser(
      ValueAndCloserConsumer<? super V> consumer, Executor executor) {
    checkNotNull(consumer);
    if (!compareAndUpdateState(OPEN, WILL_CREATE_VALUE_AND_CLOSER)) {
      switch (state.get()) {
        case SUBSUMED:
          throw new IllegalStateException(
              "Cannot call finishToValueAndCloser() after deriving another step");

   *     operation is done
   */
  public void finishToValueAndCloser(
      ValueAndCloserConsumer<? super V> consumer, Executor executor) {
    checkNotNull(consumer);
    if (!compareAndUpdateState(OPEN, WILL_CREATE_VALUE_AND_CLOSER)) {
      switch (state.get()) {
        case SUBSUMED:
          throw new IllegalStateException(
              "Cannot call finishToValueAndCloser() after deriving another step");