abstract T output(@ParametricNullness K key, @ParametricNullness V value);

    @Override
    public boolean hasNext() {
      return keyIterator.hasNext() || valueIterator.hasNext();
    }

    @Override
    @ParametricNullness
    public T next() {
      if (!valueIterator.hasNext()) {
        Entry<K, Collection<V>> mapEntry = keyIterator.next();
        key = mapEntry.getKey();

      @Nullable K currentKey = null;
      Iterator<V> valueItr = emptyIterator();

      @Override
      public boolean hasNext() {
        return valueItr.hasNext() || asMapItr.hasNext();
      }

      @Override
      public Entry<K, V> next() {
        if (!valueItr.hasNext()) {
          Entry<K, ? extends ImmutableCollection<V>> entry = asMapItr.next();
          currentKey = entry.getKey();

      @Nullable K currentKey = null;
      Iterator<V> valueItr = emptyIterator();

      @Override
      public boolean hasNext() {
        return valueItr.hasNext() || asMapItr.hasNext();
      }

      @Override
      public Entry<K, V> next() {
        if (!valueItr.hasNext()) {
          Entry<K, ? extends ImmutableCollection<V>> entry = asMapItr.next();
          currentKey = entry.getKey();

  @CollectionSize.Require(SEVERAL)
  @CollectionFeature.Require(SUPPORTS_ITERATOR_REMOVE)
  public void testIteratorRemoveMultiple() {
    Iterator<Entry<K, V>> entryItr = getMap().entrySet().iterator();
    while (entryItr.hasNext()) {
      entryItr.next();
      entryItr.remove();
    }
    assertTrue(getMap().isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(SUPPORTS_ITERATOR_REMOVE)

  @CollectionSize.Require(SEVERAL)
  @CollectionFeature.Require(SUPPORTS_ITERATOR_REMOVE)
  public void testIteratorRemoveMultiple() {
    Iterator<Entry<K, V>> entryItr = getMap().entrySet().iterator();
    while (entryItr.hasNext()) {
      entryItr.next();
      entryItr.remove();
    }
    assertTrue(getMap().isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(SUPPORTS_ITERATOR_REMOVE)

        throw new ConcurrentModificationException();
      }
    }

    @Override
    public boolean hasNext() {
      checkForConcurrentModification();
      return entryIndex >= 0;
    }

    @Override
    @ParametricNullness
    public T next() {
      if (!hasNext()) {
        throw new NoSuchElementException();
      }
      T result = result(entryIndex);
      toRemove = entryIndex;

         * throwing an IllegalStateException.
         */
        return new Iterator<T>() {
          boolean atStart = true;

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

          @Override
          @ParametricNullness
          public T next() {
            T result = iterator.next();

    assertTrue(iter.hasNext());
    Entry<String, String> entry = iter.next();
    assertEquals("Hello", entry.getKey());
    assertEquals("World", entry.getValue());
    assertTrue(iter.hasNext());

    entry = iter.next();
    assertEquals("first", entry.getKey());
    assertEquals("second", entry.getValue());
    assertTrue(iter.hasNext());

    entry = iter.next();

          Iterator<Entry<K, V>> entryIterator) {
    return new UnmodifiableIterator<Entry<K, V>>() {
      @Override
      public boolean hasNext() {
        return entryIterator.hasNext();
      }

      @Override
      public Entry<K, V> next() {
        return unmodifiableEntry(entryIterator.next());
      }
    };
  }

      @Override
      public boolean hasNext() {
        if (current == null) {
          return false;
        } else if (range.tooHigh(current.getElement())) {
          current = null;
          return false;
        } else {
          return true;
        }
      }

      @Override
      public Entry<E> next() {
        if (!hasNext()) {
          throw new NoSuchElementException();