// Make sure computeNext() doesn't get invoked again
    assertFalse(iter.hasNext());

    assertThrows(NoSuchElementException.class, iter::next);
  }

  public void testSneakyThrow() throws Exception {
    Iterator<Integer> iter =
        new AbstractIterator<Integer>() {
          boolean haveBeenCalled;

          @Override
          public Integer computeNext() {
            if (haveBeenCalled) {

   *     IllegalStateException}.
   */
  @CheckForNull
  protected abstract T computeNext();

  /**
   * Implementations of {@link #computeNext} <b>must</b> invoke this method when there are no
   * elements left in the iteration.
   *
   * @return {@code null}; a convenience so your {@code computeNext} implementation can use the
   *     simple statement {@code return endOfData();}
   */

    // second, then signals that it's reached the end of the data
    Iterator<Integer> iter =
        new AbstractIterator<Integer>() {
          private int rep;

          @Override
          public @Nullable Integer computeNext() {
            switch (rep++) {
              case 0:
                return 0;
              case 1:
                return 1;
              case 2:
                return endOfData();
              default:

    // second, then signals that it's reached the end of the data
    Iterator<Integer> iter =
        new AbstractIterator<Integer>() {
          private int rep;

          @Override
          public @Nullable Integer computeNext() {
            switch (rep++) {
              case 0:
                return 0;
              case 1:
                return 1;
              case 2:
                return endOfData();
              default:

          Set<N> seenNodes = new HashSet<>();
          return new AbstractIterator<N>() {
            @Override
            @CheckForNull
            protected N computeNext() {
              while (nodeConnections.hasNext()) {
                NodeConnection<N> nodeConnection = nodeConnections.next();
                boolean added = seenNodes.add(nodeConnection.node);

  private final Queue<T> queue;

  ConsumingQueueIterator(Queue<T> queue) {
    this.queue = checkNotNull(queue);
  }

  @Override
  @CheckForNull
  protected T computeNext() {
    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
    if (queue.isEmpty()) {
      return endOfData();
    }
    return queue.remove();
  }

  }

  @Override
  public UnmodifiableIterator<C> iterator() {
    return new AbstractSequentialIterator<C>(first()) {
      final C last = last();

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

  @GwtIncompatible // NavigableSet
  @Override

        // TODO(lowasser): consider making the entries live views
        return new AbstractIterator<Entry<E>>() {
          @Override
          @CheckForNull
          protected Entry<E> computeNext() {
            if (iterator1.hasNext()) {
              Entry<? extends E> entry1 = iterator1.next();
              E element = entry1.getElement();

        // TODO(lowasser): consider making the entries live views
        return new AbstractIterator<Entry<E>>() {
          @Override
          @CheckForNull
          protected Entry<E> computeNext() {
            if (iterator1.hasNext()) {
              Entry<? extends E> entry1 = iterator1.next();
              E element = entry1.getElement();

                  .values()
                  .iterator();
          return new AbstractIterator<Entry<Range<K>, V>>() {

            @Override
            @CheckForNull
            protected Entry<Range<K>, V> computeNext() {
              if (backingItr.hasNext()) {
                RangeMapEntry<K, V> entry = backingItr.next();
                if (entry.getUpperBound().compareTo(subRange.lowerBound) <= 0) {