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 {

   */
  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());

        }
        return root;
      }
    },
    RANDOM {
      /**
       * Generates a tree with topology selected uniformly at random from the topologies of binary
       * trees of the specified size.
       */
      @Override
      Optional<BinaryNode> createTree(int size, Random rng) {
        int[] keys = new int[size];

              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 {