@Override
    public int hashCode() {
        return value ? Boolean.TRUE.hashCode() : Boolean.FALSE.hashCode();
    }
@Test
    void requireThatHashCodeIsImplemented() {
        assertEquals(new BooleanPredicate(true).hashCode(), new BooleanPredicate(true).hashCode());
        assertEquals(new BooleanPredicate(false).hashCode(), new BooleanPredicate(false).hashCode());
    }