public boolean after(DateTimeStamp other) {
        return compareTo(other) > 0;
    }
@Test
    void testAfter() {
        DateTimeStamp a;
        DateTimeStamp b;

        a = new DateTimeStamp(.586);
        b = new DateTimeStamp(.586);
        assertFalse(b.after(a));
        assertFalse(a.after(b));
        b = new DateTimeStamp(.587);
        assertTrue(b.after(a));
        assertFalse(a.after(b));

        a = new DateTimeStamp("2018-04-04T09:10:00.586-0100");
        b = new DateTimeStamp("2018-04-04T09:10:00.586-0100");
        assertFalse(b.after(a));
        assertFalse(a.after(b));
        b = new DateTimeStamp("2018-04-04T09:10:00.587-0100");
        assertTrue(b.after(a));
        assertFalse(a.after(b));

        a = new DateTimeStamp("2018-04-04T09:10:00.586-0100", 0.18);
        b = new DateTimeStamp("2018-04-04T09:10:00.586-0100", 0.18);
        assertFalse(b.after(a));
        assertFalse(a.after(b));
        b = new DateTimeStamp("2018-04-04T09:10:00.586-0100", 0.19);
        assertTrue(b.after(a));
        assertFalse(a.after(b));

        a = new DateTimeStamp("2018-04-04T09:10:00.586-0100", 0.18);
        b = new DateTimeStamp("2018-04-04T09:10:00.586-0100", 0.18);
        assertFalse(b.after(a));
        assertFalse(a.after(b));

        a = new DateTimeStamp("2018-04-04T09:10:00.586-0100", 0.18);
        b = new DateTimeStamp("2018-04-04T09:10:00.587-0100", 0.19);
        assertTrue(b.after(a));
        assertFalse(a.after(b));
    }