return forwardMultiset().pollFirstEntry();
  }

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

  @Override
  public SortedMultiset<E> subMultiset(
      @ParametricNullness E fromElement,
      BoundType fromBoundType,
      @ParametricNullness E toElement,

    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() {

   * supports.
   *
   * <p>The returned multiset will throw an {@link IllegalArgumentException} on attempts to add
   * elements outside its range.
   *
   * <p>This method is equivalent to {@code tailMultiset(lowerBound,
   * lowerBoundType).headMultiset(upperBound, upperBoundType)}.
   */
  SortedMultiset<E> subMultiset(
      @ParametricNullness E lowerBound,
      BoundType lowerBoundType,

   * supports.
   *
   * <p>The returned multiset will throw an {@link IllegalArgumentException} on attempts to add
   * elements outside its range.
   *
   * <p>This method is equivalent to {@code tailMultiset(lowerBound,
   * lowerBoundType).headMultiset(upperBound, upperBoundType)}.
   */
  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() {

      BoundType toBoundType) {
    // 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() {

    // 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 getSubMultiset(0, elementSet.headIndex(upperBound, checkNotNull(boundType) == CLOSED));
  }

  @Override
  public ImmutableSortedMultiset<E> tailMultiset(E lowerBound, BoundType boundType) {
    return getSubMultiset(
        elementSet.tailIndex(lowerBound, checkNotNull(boundType) == CLOSED), length);
  }

      BoundType toBoundType) {
    // 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 getSubMultiset(0, elementSet.headIndex(upperBound, checkNotNull(boundType) == CLOSED));
  }

  @Override
  public ImmutableSortedMultiset<E> tailMultiset(E lowerBound, BoundType boundType) {
    return getSubMultiset(
        elementSet.tailIndex(lowerBound, checkNotNull(boundType) == CLOSED), length);
  }