public static <T> AggregateOperation1<T, List<T>, List<T>> toList() {
        return toCollection(ArrayList::new);
    }
@Test
    public void when_toList() {
        validateOpWithoutDeduct(
                toList(), identity(), 1, 2, singletonList(1), asList(1, 2), asList(1, 2));
    }