implements Iterator<T> {
  final Iterator<? extends F> backingIterator;

  TransformedIterator(Iterator<? extends F> backingIterator) {
    this.backingIterator = checkNotNull(backingIterator);
  }

  @ParametricNullness
  abstract T transform(@ParametricNullness F from);

  @Override
  public final boolean hasNext() {
    return backingIterator.hasNext();
  }

  @Override
  @ParametricNullness

  TransformedListIterator(ListIterator<? extends F> backingIterator) {
    super(backingIterator);
  }

  private ListIterator<? extends F> backingIterator() {
    return (ListIterator<? extends F>) backingIterator;
  }

  @Override
  public final boolean hasPrevious() {
    return backingIterator().hasPrevious();
  }

  @Override
  @ParametricNullness
  public final T previous() {

  TransformedListIterator(ListIterator<? extends F> backingIterator) {
    super(backingIterator);
  }

  private ListIterator<? extends F> backingIterator() {
    return (ListIterator<? extends F>) backingIterator;
  }

  @Override
  public final boolean hasPrevious() {
    return backingIterator().hasPrevious();
  }

  @Override
  @ParametricNullness
  public final T previous() {

            final Iterator<Entry<K, Collection<V>>> backingIterator =
                unfiltered.asMap().entrySet().iterator();

            @Override
            @CheckForNull
            protected Entry<K, Collection<V>> computeNext() {
              while (backingIterator.hasNext()) {
                Entry<K, Collection<V>> entry = backingIterator.next();
                K key = entry.getKey();

            final Iterator<Entry<K, Collection<V>>> backingIterator =
                unfiltered.asMap().entrySet().iterator();

            @Override
            @CheckForNull
            protected Entry<K, Collection<V>> computeNext() {
              while (backingIterator.hasNext()) {
                Entry<K, Collection<V>> entry = backingIterator.next();
                K key = entry.getKey();

    @Override
    UnmodifiableIterator<Entry<K, ImmutableSet<V>>> entryIterator() {
      final Iterator<Entry<K, V>> backingIterator = ImmutableMap.this.entrySet().iterator();
      return new UnmodifiableIterator<Entry<K, ImmutableSet<V>>>() {
        @Override
        public boolean hasNext() {
          return backingIterator.hasNext();
        }

        @Override
        public Entry<K, ImmutableSet<V>> next() {

    @Override
    UnmodifiableIterator<Entry<K, ImmutableSet<V>>> entryIterator() {
      final Iterator<Entry<K, V>> backingIterator = ImmutableMap.this.entrySet().iterator();
      return new UnmodifiableIterator<Entry<K, ImmutableSet<V>>>() {
        @Override
        public boolean hasNext() {
          return backingIterator.hasNext();
        }

        @Override
        public Entry<K, ImmutableSet<V>> next() {