@Test
public void shouldGroupIntoThreeGroupsOfSize_1_and_2_part2() throws Exception {

    List<String> input = Stream.of("a", "b", "c").collect(toList());
    List<List<List<String>>> groups = P27.group(input, Stream.of(1, 2).collect(Collectors.toList()));
    assertThat(groups, hasSize(3));
}