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

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

    public EmptyAbstractSequentialIterator() {
      super(null);
    }

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

 * whose next element can always be derived from the previous element. Null elements are not
 * supported, nor is the {@link #remove()} method.
 *
 * <p>Example:
 *
 * <pre>{@code
 * Iterator<Integer> powersOfTwo =
 *     new AbstractSequentialIterator<Integer>(1) {
 *       protected Integer computeNext(Integer previous) {
 *         return (previous == 1 << 30) ? null : previous * 2;
 *       }
 *     };
 * }</pre>
 *

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

    @Override

    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;

      prev = x;
    }
  }

  /** getAndSet returns previous value and sets to given value */
  public void testGetAndSet() {
    double prev = Math.E;
    AtomicDouble at = new AtomicDouble(prev);
    for (double x : VALUES) {
      assertBitEquals(prev, at.getAndSet(x));
      prev = x;
    }
  }

  /** getAndAdd returns previous value and adds given value */
  public void testGetAndAdd() {

      final C first = first();

      @Override
      @CheckForNull
      protected C computeNext(C previous) {
        return equalsOrThrow(previous, first) ? null : domain.previous(previous);
      }
    };
  }

  private static boolean equalsOrThrow(Comparable<?> left, @CheckForNull Comparable<?> right) {
    return right != null && Range.compareOrThrow(left, right) == 0;
  }

  @Override

/**
 * Serializes execution of tasks, somewhat like an "asynchronous {@code synchronized} block." Each
 * {@linkplain #submit enqueued} callable will not be submitted to its associated executor until the
 * previous callable has returned -- and, if the previous callable was an {@link AsyncCallable}, not
 * until the {@code Future} it returned is {@linkplain Future#isDone done} (successful, failed, or
 * cancelled).
 *

  }

  @Override
  public final boolean hasPrevious() {
    return backingIterator().hasPrevious();
  }

  @Override
  @ParametricNullness
  public final T previous() {
    return transform(backingIterator().previous());
  }

  @Override
  public final int nextIndex() {
    return backingIterator().nextIndex();
  }

  @Override
  public final int previousIndex() {

    @Override
    public Integer next(Integer value) {
      return DELEGATE.next(value);
    }

    @Override
    public Integer previous(Integer value) {
      return DELEGATE.previous(value);
    }

    // Do *not* override offset() to delegate: We want to test the default implementation.

    @Override
    public long distance(Integer start, Integer end) {

    Map<K, V> delegate = Maps.newLinkedHashMap();
    for (Entry<? extends K, ? extends V> entry : entries) {
      K key = checkNotNull(entry.getKey());
      V previous = delegate.put(key, checkNotNull(entry.getValue()));
      if (throwIfDuplicateKeys && previous != null) {
        throw new IllegalArgumentException("duplicate key: " + key);
      }
    }
    this.delegate = Collections.unmodifiableMap(delegate);
  }