}

    /**
     * Checks if there is a previous page available.
     *
     * @return true if there is a previous page, false otherwise
     */
    public boolean isExistPrePage() {
        return existPrePage;
    }

    /**
     * Sets whether there is a previous page available.
     *
     * @param existPrePage true if there is a previous page, false otherwise
     */

      protected @Nullable Integer computeNext(Integer previous) {
        return (previous == last) ? null : previous * 2;
      }
    };
  }

  private static class EmptyAbstractSequentialIterator<T> extends AbstractSequentialIterator<T> {

    EmptyAbstractSequentialIterator() {
      super(null);
    }

    @Override
    protected T computeNext(T previous) {
      throw new AssertionFailedError();
    }

    monitor.enter();
    try {
      State previous = state();
      switch (previous) {
        case NEW:
        case TERMINATED:
          throw new IllegalStateException("Failed while in state:" + previous, cause);
        case RUNNING:
        case STARTING:
        case STOPPING:
          snapshot = new StateSnapshot(FAILED, false, cause);
          enqueueFailedEvent(previous, cause);
          break;

    }

    /**
     * Returns true if a previous page exists.
     *
     * @return True if a previous page exists.
     */
    public boolean isExistPrePage() {
        return existPrePage;
    }

    /**
     * Sets whether a previous page exists.
     *
     * @param existPrePage True if a previous page exists.
     */

    }

    /**
     * Checks if a previous page exists.
     *
     * @return True if a previous page exists, false otherwise
     */
    public boolean isExistPrePage() {
        return existPrePage;
    }

    /**
     * Sets whether a previous page exists.
     *
     * @param existPrePage True if a previous page exists
     */

        case OPEN:
          C previous = domain.previous(endpoint);
          return (previous == null) ? Cut.belowAll() : new AboveValue<>(previous);
      }
      throw new AssertionError();
    }

    @Override
    Cut<C> withUpperBoundType(BoundType boundType, DiscreteDomain<C> domain) {
      switch (boundType) {
        case CLOSED:
          C previous = domain.previous(endpoint);

    }

    /**
     * Checks if a previous page exists for pagination.
     *
     * @return true if a previous page exists, false otherwise
     */
    public boolean isExistPrePage() {
        return existPrePage;
    }

    /**
     * Sets the flag indicating whether a previous page exists.
     *
     * @param existPrePage true if a previous page exists, false otherwise
     */

    rateLimiter.acquire(1); // R1.00, to repay previous

    rateLimiter.setRate(2.0); // update the rate!

    rateLimiter.acquire(1); // R1.00, to repay previous (the previous was under the old rate!)
    rateLimiter.acquire(2); // R0.50, to repay previous (now the rate takes effect)
    rateLimiter.acquire(4); // R1.00, to repay previous
    rateLimiter.acquire(1); // R2.00, to repay previous

    rateLimiter.acquire(1); // R1.00, to repay previous

    rateLimiter.setRate(2.0); // update the rate!

    rateLimiter.acquire(1); // R1.00, to repay previous (the previous was under the old rate!)
    rateLimiter.acquire(2); // R0.50, to repay previous (now the rate takes effect)
    rateLimiter.acquire(4); // R1.00, to repay previous
    rateLimiter.acquire(1); // R2.00, to repay previous

    }

    /**
     * Checks if there is a previous page.
     * @return true if previous page exists, false otherwise
     */
    public boolean isExistPrePage() {
        return existPrePage;
    }

    /**
     * Sets whether a previous page exists.
     * @param existPrePage true if previous page exists
     */
    public void setExistPrePage(final boolean existPrePage) {