public override void Remove(Component c)
 {
     Console.WriteLine("Cannot remove leaf");
 }
 public override void Add(Component c)
 {
     Console.WriteLine("Cannot add to leaf");
 }
 public override void Remove(Component component)
 {
     this._children.Remove(component);
 }
 public override void Add(Component component)
 {
     this._children.Add(component);
 }
 public abstract void Remove(Component c);
 public abstract void Add(Component c);