public void Set(CompactQuadTree <T> tree, T value)
 {
     tree[this] = value;
 }
 public bool IsLeaf(CompactQuadTree <T> tree)
 {
     return(Index >= tree.lastLevelFirstNodeIndex);
 }
 public T Get(CompactQuadTree <T> tree)
 {
     return(tree[this]);
 }