@SuppressWarnings("unchecked")
  // if sortedSet.comparator() is null, the set must be naturally ordered
  public static <E extends @Nullable Object> Comparator<? super E> comparator(
      SortedSet<E> sortedSet) {
    Comparator<? super E> result = sortedSet.comparator();
    if (result == null) {
      result = (Comparator<? super E>) Ordering.natural();
    }
    return result;
  }

     * Anyway, the purpose of this method is to implement a BinaryOperator combiner for a Collector,
     * so its return value will get used naturally.
     */
    @SuppressWarnings("CanIgnoreReturnValueSuggester")
    ImmutableTableCollectorState<R, C, V> combine(
        ImmutableTableCollectorState<R, C, V> other, BinaryOperator<V> merger) {

     * Anyway, the purpose of this method is to implement a BinaryOperator combiner for a Collector,
     * so its return value will get used naturally.
     */
    @SuppressWarnings("CanIgnoreReturnValueSuggester")
    ImmutableTableCollectorState<R, C, V> combine(
        ImmutableTableCollectorState<R, C, V> other, BinaryOperator<V> merger) {

    assertTrue(isInOrder(ImmutableList.of(), Ordering.natural()));
  }

  public void testIsInStrictOrder() {
    assertFalse(isInStrictOrder(asList(5, 3, 0, 9), Ordering.natural()));
    assertFalse(isInStrictOrder(asList(0, 5, 3, 9), Ordering.natural()));
    assertTrue(isInStrictOrder(asList(0, 3, 5, 9), Ordering.natural()));
    assertFalse(isInStrictOrder(asList(0, 0, 3, 3), Ordering.natural()));

  }

  @Test
  public void nodeOrder_natural() {
    MutableGraph<Integer> graph =
        GraphBuilder.directed().nodeOrder(ElementOrder.<Integer>natural()).build();

    addNodes(graph);

    assertThat(graph.nodeOrder()).isEqualTo(ElementOrder.sorted(Ordering.<Integer>natural()));
    assertThat(graph.nodes()).containsExactly(1, 3, 4).inOrder();
  }

  @Test
  public void nodeOrder_sorted() {

    implements SortedMultiset<E> {
  private final Comparator<? super E> comparator;

  // needed for serialization
  @SuppressWarnings("unchecked")
  AbstractSortedMultiset() {
    this((Comparator) Ordering.natural());
  }

  AbstractSortedMultiset(Comparator<? super E> comparator) {
    this.comparator = checkNotNull(comparator);
  }

  @Override
  public SortedSet<E> elementSet() {

    assertTrue(SortedIterables.hasSameComparator(Ordering.natural(), Sets.newTreeSet()));
    assertTrue(SortedIterables.hasSameComparator(Ordering.natural(), Maps.newTreeMap().keySet()));
    assertTrue(
        SortedIterables.hasSameComparator(
            Ordering.natural().reverse(), Sets.newTreeSet(Ordering.natural().reverse())));
  }

  public void testComparator() {
    assertEquals(Ordering.natural(), SortedIterables.comparator(Sets.newTreeSet()));

    assertThat(copy.keySet()).containsExactly("google", "tree").inOrder();
    assertThat(copy.get("google")).containsExactly(2, 6).inOrder();
    assertEquals(Ordering.natural(), copy.keyComparator());
    assertEquals(Ordering.natural(), copy.valueComparator());
    assertEquals(Ordering.natural(), copy.get("google").comparator());
  }

  public void testToString() {
    Multimap<String, Integer> multimap = create();
    multimap.put("foo", 3);

  }

  public void testFromRangeAll() {
    assertEquals(GeneralRange.all(Ordering.natural()), GeneralRange.from(Range.all()));
  }

  public void testFromRangeOneEnd() {
    for (BoundType endpointType : BoundType.values()) {
      assertEquals(
          GeneralRange.upTo(Ordering.natural(), 3, endpointType),
          GeneralRange.from(Range.upTo(3, endpointType)));

      assertEquals(

  }

  public void testFromRangeAll() {
    assertEquals(GeneralRange.all(Ordering.natural()), GeneralRange.from(Range.all()));
  }

  public void testFromRangeOneEnd() {
    for (BoundType endpointType : BoundType.values()) {
      assertEquals(
          GeneralRange.upTo(Ordering.natural(), 3, endpointType),
          GeneralRange.from(Range.upTo(3, endpointType)));

      assertEquals(