}

  public void testToList() {
    assertEquals(Lists.newArrayList(1, 2, 3, 4), fluent(1, 2, 3, 4).toList());
  }

  public void testToList_empty() {
    assertTrue(fluent().toList().isEmpty());
  }

  public void testToSortedList_withComparator() {
    assertEquals(
        Lists.newArrayList(4, 3, 2, 1),