public int ceil(T v) {
        return Boundary.CEIL.apply(find(v));
    }
@Test
    public void testCeil() {
        assertEquals(0, l.ceil("A"));
        assertEquals(0, l.ceil("B"));
        assertEquals(1, l.ceil("C"));
        assertEquals(1, l.ceil("D"));
        assertEquals(2, l.ceil("E"));
        assertEquals(2, l.ceil("F"));
        assertEquals(3, l.ceil("G"));
    }