public void testGetLast_basic() {
    List<String> list = new ArrayList<>();
    list.add("a");
    list.add("b");
    assertEquals("b", getLast(list.iterator()));
  }

  public void testGetLast_exception() {
    List<String> list = new ArrayList<>();
    assertThrows(NoSuchElementException.class, () -> getLast(list.iterator()));
  }

  public void testGetLast_withDefault_singleton() {