public override INodeState <T> GetFlyweight(int positionId, NodeFlyweightFactory <T> factory)
 {
     throw new System.NotImplementedException();
 }
 public new VertexNodeState <T> Contents(int positionId, NodeFlyweightFactory <T> factory)
 {
     return((VertexNodeState <T>) this.GetFlyweight(positionId, factory));
 }