@Override
    public void remove() {
      checkForConcurrentModification();
      CollectPreconditions.checkRemove(toRemove != -1);
      size -= backingMap.removeEntry(toRemove);
      entryIndex = backingMap.nextIndexAfterRemove(entryIndex, toRemove);
      toRemove = -1;
      expectedModCount = backingMap.modCount;
    }
  }

  @Override
  final Iterator<E> elementIterator() {
    return new Itr<E>() {