return node.children;
            }
          });

  //        h
  //      / | \
  //     /  e  \
  //    d       g
  //   /|\      |
  //  / | \     f
  // a  b  c
  static final Tree a = new Tree('a');
  static final Tree b = new Tree('b');
  static final Tree c = new Tree('c');
  static final Tree d = new Tree('d', a, b, c);
  static final Tree e = new Tree('e');

    tree.put("tree", 3);
    assertThat(tree.keySet()).containsExactly("tree", "google").inOrder();
    assertThat(tree.get("google")).containsExactly(6, 2).inOrder();

    TreeMultimap<String, Integer> copy = TreeMultimap.create(tree);
    assertEquals(tree, copy);
    assertThat(copy.keySet()).containsExactly("google", "tree").inOrder();
    assertThat(copy.get("google")).containsExactly(2, 6).inOrder();

  @Test
  public void forGraph_breadthFirst_tree() throws Exception {
    Traverser<Character> traverser = Traverser.forGraph(TREE);

    assertEqualCharNodes(traverser.breadthFirst('h'), "hdegabcf");
    assertEqualCharNodes(traverser.breadthFirst('d'), "dabc");
    assertEqualCharNodes(traverser.breadthFirst('a'), "a");
  }

  @Test
  public void forGraph_breadthFirstIterable_tree() throws Exception {

      }
    },
    SyncHM {
      @Override
      Map<Element, Element> create(Collection<Element> keys) {
        return Collections.synchronizedMap(Hash.create(keys));
      }
    },
    Tree {
      @Override
      Map<Element, Element> create(Collection<Element> keys) {
        Map<Element, Element> map = Maps.newTreeMap();
        for (Element element : keys) {
          map.put(element, element);
        }

   */
  public void testCreateFromTreeMultimap() {
    Multimap<Double, Double> tree = TreeMultimap.create(KEY_COMPARATOR, VALUE_COMPARATOR);
    tree.put(1.0, 2.0);
    tree.put(2.0, 3.0);
    tree.put(3.0, 4.0);
    tree.put(4.0, 5.0);

    TreeMultimap<Double, Double> copyFromTree = TreeMultimap.create(tree);
    assertEquals(tree, copyFromTree);
    assertSame(Ordering.natural(), copyFromTree.keyComparator());

  public static <N> Traverser<N> forTree(SuccessorsFunction<N> tree) {
    if (tree instanceof BaseGraph) {
      checkArgument(((BaseGraph<?>) tree).isDirected(), "Undirected graphs can never be trees.");
    }
    if (tree instanceof Network) {
      checkArgument(((Network<?, ?>) tree).isDirected(), "Undirected networks can never be trees.");
    }
    return new Traverser<N>(tree) {
      @Override
      Traversal<N> newTraversal() {

   */
  public void testCreateFromTreeMultimap() {
    Multimap<Double, Double> tree = TreeMultimap.create(KEY_COMPARATOR, VALUE_COMPARATOR);
    tree.put(1.0, 2.0);
    tree.put(2.0, 3.0);
    tree.put(3.0, 4.0);
    tree.put(4.0, 5.0);

    TreeMultimap<Double, Double> copyFromTree = TreeMultimap.create(tree);
    assertEquals(tree, copyFromTree);
    assertSame(Ordering.natural(), copyFromTree.keyComparator());

   * {@link #ignoreClasses} to exclude generated classes, such as the {@code AutoValue_Foo} classes
   * generated by <a href="https://github.com/google/auto/tree/master/value">AutoValue</a>.
   *
   * @since 19.0
   */
  public static final Predicate<Class<?>> UNDERSCORE_IN_NAME =
      (Class<?> c) -> c.getSimpleName().contains("_");

   *       </ul>
   *   <li>another java.util.Set delegate implementation. In most modern JDKs, normal java.util hash
   *       collections intelligently fall back to a binary search tree if hash table collisions are
   *       detected. Rather than going to all the trouble of reimplementing this ourselves, we
   *       simply switch over to use the JDK implementation wholesale if probable hash flooding is

    tree.put("tree", 3);
    assertThat(tree.keySet()).containsExactly("tree", "google").inOrder();
    assertThat(tree.get("google")).containsExactly(6, 2).inOrder();

    TreeMultimap<String, Integer> copy = TreeMultimap.create(tree);
    assertEquals(tree, copy);
    assertThat(copy.keySet()).containsExactly("google", "tree").inOrder();
    assertThat(copy.get("google")).containsExactly(2, 6).inOrder();