class Leaf implements IComponent {
            private String id;

            public Leaf(String id) {
                    this.id = id;
            }

            public String toString() {
                    return this.id;
            }

            public Collection getChildren() {
                    return null;
            }

            // false because failed to add
            public boolean addComponent(IComponent c) {
                    return false;
            }

            // false because failed to find it for removal
            public boolean removeComponent(IComponent c) {
                    return false;
            }
    }