    @Test
    public void isChild() {

        INode node1 = new Node();
        INode node2 = new Node();
        node1.insert(node2);
        Node node3 = new Node();
        node2.insert(node3);
        ExpandableList list = new ExpandableList();
        assertFalse(list.isChild(node3));
        list.insert(node1);
        assertTrue(list.isChild(node3));
    }