public virtual ReadOnlyCollection <PathfindingNode <T> > Neighbors(PathfindingNode <T> tile)
{
throw new System.NotImplementedException();
// return all the neighbors to this node
}
public virtual PathfindingEdge <T> JoiningEdge(PathfindingNode <T> node)
{
throw new System.NotImplementedException();
// return the edge connecting this node and the passed in neighbor. Throw an exception if they are not connected.
}