public void UsageMethod()
 {
     Composite root = new Composite("root");
     root.Add(new Leaf("Branch 1A"));
     root.Add(new Leaf("Branch 1B"));
     Composite comp = new Composite("Composite X");
     comp.Add(new Leaf("Branch 2A"));
     comp.Add(new Leaf("Branch 2B"));
     root.Add(comp);
     root.Add(new Leaf("Branch C"));
     Leaf branch = new Leaf("Branch D");
     root.Add(branch);
     root.Remove(branch);
     root.Display(1);
 }