set.remove("b");
    set.addAll(Lists.newArrayList("X", "Y", "Z"));
    assertThat(tail).containsExactly("c", "X", "Y", "Z").inOrder();
  }

  public void testSkip_structurallyModifiedSkipSomeList() throws Exception {
    List<String> list = Lists.newArrayList("a", "b", "c");
    FluentIterable<String> tail = FluentIterable.from(list).skip(1);
    list.subList(1, 3).clear();

    Iterable<String> tail = skip(set, 1);
    set.remove("b");
    set.addAll(newArrayList("A", "B", "C"));
    assertThat(tail).containsExactly("c", "A", "B", "C").inOrder();
  }

  public void testSkip_structurallyModifiedSkipSomeList() throws Exception {
    List<String> list = newArrayList("a", "b", "c");
    Iterable<String> tail = skip(list, 1);
    list.subList(1, 3).clear();
    list.addAll(0, newArrayList("A", "B", "C"));