/** Constructor for use by subclasses. */
  protected AbstractIterator() {}

  private enum State {
    /** We have computed the next element and haven't returned it yet. */
    READY,

    /** We haven't yet computed or have already returned the element. */
    NOT_READY,

    /** We have reached the end of the data and are finished. */
    DONE,

    /** We've suffered an exception and are kaput. */

        indexToRemove = currentIndex;
        E result = element(currentIndex);
        currentIndex = getSuccessor(currentIndex);
        return result;
      }

      @Override
      public void remove() {
        checkForConcurrentModification();
        checkRemove(indexToRemove >= 0);
        incrementExpectedModCount();
        CompactHashSet.this.remove(element(indexToRemove));

      }
    }

    return !iteratorA.hasNext() && !iteratorB.hasNext();
  }

  @Override
  protected int doHash(Iterable<T> iterable) {
    int hash = 78721;
    for (T element : iterable) {
      hash = hash * 24943 + elementEquivalence.hash(element);
    }
    return hash;
  }

  @Override
  public boolean equals(@Nullable Object obj) {
    if (obj instanceof PairwiseEquivalence) {
      @SuppressWarnings("unchecked")

  DescendingImmutableSortedMultiset(ImmutableSortedMultiset<E> forward) {
    this.forward = forward;
  }

  @Override
  public int count(@Nullable Object element) {
    return forward.count(element);
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    return forward.lastEntry();
  }

  @Override
  public @Nullable Entry<E> lastEntry() {
    return forward.firstEntry();

            eventType = parser.next();
        }
        if (parsed) {
            return coreExtensions;
        }
        throw new XmlPullParserException(
                "Expected root element 'extensions' but found no element at all: invalid XML document", parser, null);
    } // -- CoreExtensions read( XmlPullParser, boolean )

    /**
     * @see XmlStreamReader
     *
     * @param reader a reader object.

   * nulls as long as the *last* element is *not* null.
   *
   * (To "go out of its way," the method tracks a `set` bit so that it can distinguish "the final
   * split has a last element of null, so throw NPE" from "the final split was empty, so look for an
   * element in the prior one.")
   */
  public static <T> java.util.Optional<T> findLast(Stream<T> stream) {

  public void testPoll_size1() {
    assertEquals("size1Queue.poll() should return first element", e0(), getQueue().poll());
    expectMissing(e0());
  }

  @CollectionFeature.Require({KNOWN_ORDER, SUPPORTS_REMOVE})
  @CollectionSize.Require(SEVERAL)
  public void testPoll_sizeMany() {
    assertEquals("sizeManyQueue.poll() should return first element", e0(), getQueue().poll());
    expectMissing(e0());
  }

        final Object array = Array.newInstance(toType.getRawType(), collection.size());

        int i = 0;
        for (final Object element : collection) {
            Array.set(array, i++, element);
        }

        return array;
    }

    /**
     * Parses a sequence of XML elements and converts them to the appropriate bean type.
     *

  private int position;

  /** Returns the element with the specified index. This method is called by {@link #next()}. */
  @ParametricNullness
  protected abstract E get(int index);

  /**
   * Constructs an iterator across a sequence of the given size whose initial position is 0. That
   * is, the first call to {@link #next()} will return the first element (or throw {@link
   * NoSuchElementException} if {@code size} is zero).

              @Override
              public Collection<String> create(String[] elements) {
                // TODO: MinimalCollection should perhaps throw
                for (Object element : elements) {
                  if (element == null) {
                    throw new NullPointerException();
                  }
                }
                return MinimalCollection.of(elements);
              }
            })