}
    } else {
      node = header.pred();
    }
    return (node == header || !range.contains(node.getElement())) ? null : node;
  }

  @Override
  Iterator<E> elementIterator() {
    return Multisets.elementIterator(entryIterator());
  }

  @Override
  Iterator<Entry<E>> entryIterator() {
    return new Iterator<Entry<E>>() {
      private @Nullable AvlNode<E> current = firstNode();