assertEquals(
        Lists.newArrayList(4, 3, 2, 1),
        fluent(4, 1, 3, 2).toSortedList(Ordering.<Integer>natural().reverse()));
  }

  public void testToSortedList_withDuplicates() {
    assertEquals(
        Lists.newArrayList(4, 3, 1, 1),
        fluent(1, 4, 1, 3).toSortedList(Ordering.<Integer>natural().reverse()));
  }

  public void testToSet() {