entry = Multisets.immutableEntry(entry.getElement(), entry.getCount());
    entryIterator.remove();
    return entry;
  }

  @Override
  public SortedMultiset<E> headMultiset(E upperBound, BoundType boundType) {
    return delegate().headMultiset(upperBound, boundType);
  }

  @Override
  public SortedMultiset<E> subMultiset(
      E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType) {

    entryIterator.remove();
    return entry;
  }

  @Override
  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {
    return delegate().headMultiset(upperBound, boundType);
  }

  @Override
  public SortedMultiset<E> subMultiset(
      @ParametricNullness E lowerBound,
      BoundType lowerBoundType,

    return forward;
  }

  @Override
  public ImmutableSortedMultiset<E> headMultiset(E upperBound, BoundType boundType) {
    return forward.tailMultiset(upperBound, boundType).descendingMultiset();
  }

  @Override
  public ImmutableSortedMultiset<E> tailMultiset(E lowerBound, BoundType boundType) {
    return forward.headMultiset(lowerBound, boundType).descendingMultiset();
  }

  @Override
  boolean isPartialView() {

  }

  @Override
  public @Nullable Entry<E> pollLastEntry() {
    throw new UnsupportedOperationException();
  }

  @Override
  public SortedMultiset<E> headMultiset(E upperBound, BoundType boundType) {
    return Multisets.unmodifiableSortedMultiset(delegate().headMultiset(upperBound, boundType));
  }

  @Override
  public SortedMultiset<E> subMultiset(

  @Override
  public @Nullable Entry<E> pollLastEntry() {
    throw new UnsupportedOperationException();
  }

  @Override
  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {
    return Multisets.unmodifiableSortedMultiset(delegate().headMultiset(upperBound, boundType));
  }

  @Override
  public SortedMultiset<E> subMultiset(
      @ParametricNullness E lowerBound,

    entryIterator.remove();
    return entry;
  }

  @Override
  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {
    return delegate().headMultiset(upperBound, boundType);
  }

  @Override
  public SortedMultiset<E> subMultiset(
      @ParametricNullness E lowerBound,
      BoundType lowerBoundType,

    }

    @Override
    public @Nullable E lower(@ParametricNullness E e) {
      return getElementOrNull(multiset().headMultiset(e, OPEN).lastEntry());
    }

    @Override
    public @Nullable E floor(@ParametricNullness E e) {
      return getElementOrNull(multiset().headMultiset(e, CLOSED).lastEntry());
    }

    @Override
    public @Nullable E ceiling(@ParametricNullness E e) {

    // These are checked elsewhere, but NullPointerTester wants them checked eagerly.
    checkNotNull(fromBoundType);
    checkNotNull(toBoundType);
    return tailMultiset(fromElement, fromBoundType).headMultiset(toElement, toBoundType);
  }

  abstract Iterator<Entry<E>> descendingEntryIterator();

  Iterator<E> descendingIterator() {
    return Multisets.iteratorImpl(descendingMultiset());
  }

    return forward;
  }

  @Override
  public ImmutableSortedMultiset<E> headMultiset(E upperBound, BoundType boundType) {
    return forward.tailMultiset(upperBound, boundType).descendingMultiset();
  }

  @Override
  public ImmutableSortedMultiset<E> tailMultiset(E lowerBound, BoundType boundType) {
    return forward.headMultiset(lowerBound, boundType).descendingMultiset();
  }

  @Override
  boolean isPartialView() {

    return forwardMultiset().pollLastEntry();
  }

  @Override
  public @Nullable Entry<E> pollLastEntry() {
    return forwardMultiset().pollFirstEntry();
  }

  @Override
  public SortedMultiset<E> headMultiset(E toElement, BoundType boundType) {
    return forwardMultiset().tailMultiset(toElement, boundType).descendingMultiset();
  }

  @Override
  public SortedMultiset<E> subMultiset(