assertEquals(tree, copyFromTree);
    assertSame(Ordering.natural(), copyFromTree.keyComparator());
    assertSame(Ordering.natural(), copyFromTree.valueComparator());
    assertSame(Ordering.natural(), copyFromTree.get(1.0).comparator());
  }

  /** Test that creating one TreeMultimap from a non-TreeMultimap results in natural ordering. */
  public void testCreateFromHashMultimap() {

  }

  @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

@ElementTypesAreNonnullByDefault
public final class ImmutableSortedMap<K, V> extends ForwardingImmutableMap<K, V>
    implements SortedMap<K, V> {

  @SuppressWarnings("unchecked")
  static final Comparator<?> NATURAL_ORDER = Ordering.natural();

  // This reference is only used by GWT compiler to infer the keys and values
  // of the map that needs to be serialized.
  private @Nullable Comparator<? super K> unusedComparatorForSerialization;

    ImmutableTable.Builder<Character, Integer, String> builder = ImmutableTable.builder();
    Table<Character, Integer, String> copy =
        builder
            .orderRowsBy(Ordering.natural())
            .orderColumnsBy(Ordering.natural())
            .putAll(table)
            .build();
    assertThat(copy.rowKeySet()).containsExactly('a', 'b').inOrder();
    assertThat(copy.columnKeySet()).containsExactly(1, 2).inOrder();

    assertTrue(Comparators.isInOrder(Collections.singleton(1), Ordering.natural()));
    assertTrue(Comparators.isInOrder(Collections.<Integer>emptyList(), Ordering.natural()));
  }

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

   * ordering.
   *
   * @throws NullPointerException if any element is null
   */
  public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E e1, E e2, E e3) {
    return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3));
  }

  /**
   * Returns an immutable sorted multiset containing the given elements sorted by their natural
   * ordering.
   *

    assertTrue(Comparators.isInOrder(Collections.singleton(1), Ordering.natural()));
    assertTrue(Comparators.isInOrder(Collections.<Integer>emptyList(), Ordering.natural()));
  }

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

  /**
   * Creates an empty {@code TreeMultimap} ordered by the natural ordering of its keys and values.
   */
  @SuppressWarnings("rawtypes") // https://github.com/google/guava/issues/989
  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create() {
    return new TreeMultimap<>(Ordering.natural(), Ordering.natural());
  }

  /**

   */
  private static final Comparator<?> NATURAL_ORDER = Ordering.natural();

  private static final ImmutableSortedMap<Comparable<?>, Object> NATURAL_EMPTY_MAP =
      new ImmutableSortedMap<>(
          ImmutableSortedSet.emptySet(Ordering.natural()), ImmutableList.<Object>of());

  static <K, V> ImmutableSortedMap<K, V> emptyMap(Comparator<? super K> comparator) {
    if (Ordering.natural().equals(comparator)) {
      return of();

    assertEquals(tree, copyFromTree);
    assertSame(Ordering.natural(), copyFromTree.keyComparator());
    assertSame(Ordering.natural(), copyFromTree.valueComparator());
    assertSame(Ordering.natural(), copyFromTree.get(1.0).comparator());
  }

  /** Test that creating one TreeMultimap from a non-TreeMultimap results in natural ordering. */
  public void testCreateFromHashMultimap() {