@Override
    public long inc() {
        long l = (long) VALUE.getOpaque(this) + 1;
        VALUE.setOpaque(this, l);
        return l;
    }
@Test
    public void test_inc_withAmount() {
        assertEquals(10, counter.inc(10));
        assertEquals(10, counter.inc(0));
        assertEquals(0, counter.inc(-10));
    }