@Test
public void shouldReturnAListWithTwoListElementsWhenAListWithTwoUniqueElementsIsPassed() throws Exception {

    List<List<String>> packedList = P09.pack(Arrays.asList("a", "b"));
    assertThat(packedList, hasSize(2));
    assertThat(packedList.get(0), contains("a"));
    assertThat(packedList.get(1), contains("b"));
}