}

  public void testPollFirstEntry() {
    create().pollFirstEntry();
  }

  public void testPollLastEntry() {
    create().pollLastEntry();
  }

  public void testSubMap_k_k() {
    NavigableMap<String, Integer> map = create();
    SortedMap<String, Integer> subMap = map.subMap("a", "b");
    assertTrue(subMap instanceof SynchronizedSortedMap);