private static void TreeTest()
{
Tree <int> tree = new Tree <int>(4);
List <Tree <int> > children = tree.AddChildrenYielded(-2, -9642).ToList();
foreach (var child in children)
{
int i = child.Value;
child.AddChildren(i, i + 1, i + 2, i + 3);
}
IEnumerable <int> iter = TreeIter.BreadthFirstByValue(tree);
Console.WriteLine(String.Join(' ', iter.ToArray()));
}