public ListIterator<NODE> listIterator() {
        return vector.listIterator();
    }
@Test
    void require_that_iterators_work() {
        String val = "foo";
        TestNodeVector v = new TestNodeVector(val, val, val);
        assertTrue(v.listIterator().hasNext());
        assertTrue(v.listIterator(0).hasNext());
        assertTrue(v.listIterator(1).hasNext());
        assertTrue(v.listIterator(2).hasNext());
        assertFalse(v.listIterator(3).hasNext());
    }