final Iterator<Map<C, V>> mapIterator = backingMap.values().iterator();
    Iterator<Entry<C, V>> entryIterator = emptyIterator();

    @Override
    protected @Nullable C computeNext() {
      while (true) {
        if (entryIterator.hasNext()) {
          Entry<C, V> entry = entryIterator.next();
          if (!seen.containsKey(entry.getKey())) {
            seen.put(entry.getKey(), entry.getValue());

      return backingMultiset;
    }

    @Override
    public SortedMultiset<E> descendingMultiset() {
      return new StandardDescendingMultiset() {

        @Override
        Iterator<Entry<E>> entryIterator() {
          return backingMultiset.descendingMultiset().entrySet().iterator();
        }
      };
    }

    @Override
    public NavigableSet<E> elementSet() {
      return new StandardElementSet();

      return backingMultiset;
    }

    @Override
    public SortedMultiset<E> descendingMultiset() {
      return new StandardDescendingMultiset() {

        @Override
        Iterator<Entry<E>> entryIterator() {
          return backingMultiset.descendingMultiset().entrySet().iterator();
        }
      };
    }

    @Override
    public NavigableSet<E> elementSet() {
      return new StandardElementSet();

  @Override
  public UnmodifiableIterator<E> iterator() {
    Iterator<Entry<E>> entryIterator = entrySet().iterator();
    return new UnmodifiableIterator<E>() {
      int remaining;
      @Nullable E element;

      @Override
      public boolean hasNext() {
        return (remaining > 0) || entryIterator.hasNext();
      }

      @Override
      public E next() {
        if (remaining <= 0) {

    @Override
    protected List<V> delegate() {
      return emptyList();
    }
  }

  @Override
  Iterator<Entry<K, V>> entryIterator() {
    throw new AssertionError("should never be called");
  }

  @Override
  Collection<Entry<K, V>> createEntries() {
    return new Entries();
  }

  @WeakOuter

    @Override
    protected List<V> delegate() {
      return emptyList();
    }
  }

  @Override
  Iterator<Entry<K, V>> entryIterator() {
    throw new AssertionError("should never be called");
  }

  @Override
  Collection<Entry<K, V>> createEntries() {
    return new Entries();
  }

  @WeakOuter

  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeInt(size());
    Iterator<Entry<K, V>> entryIterator = entrySetIterator();
    while (entryIterator.hasNext()) {
      Entry<K, V> e = entryIterator.next();
      stream.writeObject(e.getKey());
      stream.writeObject(e.getValue());
    }
  }

  @SuppressWarnings("unchecked")

   *
   * <p>In particular, this map iterates over entries with repeated calls to {@link
   * NavigableMap#lowerEntry}. If a more efficient means of iteration is available, you may wish to
   * override the {@code entryIterator()} method of this class.
   *
   * @since 12.0
   */
  protected class StandardDescendingMap extends Maps.DescendingMap<K, V> {
    /** Constructor for use by subclasses. */
    public StandardDescendingMap() {}

   *
   * <p>In particular, this map iterates over entries with repeated calls to {@link
   * NavigableMap#lowerEntry}. If a more efficient means of iteration is available, you may wish to
   * override the {@code entryIterator()} method of this class.
   *
   * @since 12.0
   */
  protected class StandardDescendingMap extends Maps.DescendingMap<K, V> {
    /** Constructor for use by subclasses. */
    public StandardDescendingMap() {}

    return new Itr<E>() {
      @Override
      E output(int index) {
        return enumConstants[index];
      }
    };
  }

  @Override
  Iterator<Entry<E>> entryIterator() {
    return new Itr<Entry<E>>() {
      @Override
      Entry<E> output(int index) {
        return new Multisets.AbstractEntry<E>() {
          @Override
          public E getElement() {