public override bool RemoveAt(uint index, uint count, IAListTreeObserver <K, T> tob) { Debug.Assert(!_isFrozen); if (tob != null) { tob.RemovingItems(_list, (int)index, (int)count, this, false); } _list.RemoveRange((int)index, (int)count); return((_list.Count << 1) <= _maxNodeSize && IsUndersized); }