svoid test_subList_sanity() {
  L l = ll("a", "b");
  assertEquals(ll("a"), subList(l, 0, 1));
  assertEquals(ll("a"), subList(l, -1, 1));
  assertEquals(ll("b"), subList(l, 1));
  assertEquals(ll(), subList(l, 3));
  assertEquals(ll(), subList(l, 1, -1));
  
  subList(l, 1, 2).clear();
  assertEqualsVerbose(ll("a"), l);
}