Iterable<String> tail = skip(set, 2);
    set.remove("a");
    set.remove("b");
    assertFalse(tail.iterator().hasNext());
  }

  public void testSkip_structurallyModifiedSkipAllList() throws Exception {
    List<String> list = newArrayList("a", "b", "c");
    Iterable<String> tail = skip(list, 2);
    list.subList(0, 2).clear();
    assertTrue(Iterables.isEmpty(tail));
  }