}

  @Test
  public void forGraph_breadthFirstIterable_twoTrees() {
    assertEqualCharNodes(Traverser.forGraph(TWO_TREES).breadthFirst(charactersOf("a")), "ab");
    assertEqualCharNodes(Traverser.forGraph(TWO_TREES).breadthFirst(charactersOf("ac")), "acbd");
  }

  @Test
  public void forGraph_breadthFirst_singleRoot() {
    Iterable<Character> result = Traverser.forGraph(SINGLE_ROOT).breadthFirst('a');

  }

  @Test
  public void forGraph_breadthFirstIterable_twoTrees() {
    assertEqualCharNodes(Traverser.forGraph(TWO_TREES).breadthFirst(charactersOf("a")), "ab");
    assertEqualCharNodes(Traverser.forGraph(TWO_TREES).breadthFirst(charactersOf("ac")), "acbd");
  }

  @Test
  public void forGraph_breadthFirst_singleRoot() {
    Iterable<Character> result = Traverser.forGraph(SINGLE_ROOT).breadthFirst('a');

 *   <li>(1) "no" and (2) "no", use {@link #forGraph(SuccessorsFunction)}.
 *   <li>(1) "yes" and (2) "yes", use {@link #forTree(SuccessorsFunction)}.
 *   <li>(1) "yes" and (2) "no", you can use either, but {@code forTree()} will be more efficient.
 *   <li>(1) "no" and (2) "yes", <b><i>neither will work</i></b>, but if you transform your node
 *       objects into a non-recursive form, you can use {@code forGraph()}.
 * </ul>
 *
 * @author Jens Nyman

   */
  public static <N> ImmutableSet<N> reachableNodes(Graph<N> graph, N node) {
    checkArgument(graph.nodes().contains(node), NODE_NOT_IN_GRAPH, node);
    return ImmutableSet.copyOf(Traverser.forGraph(graph).breadthFirst(node));
  }

  // Graph mutation methods

  // Graph view methods

  /**
   * Returns a view of {@code graph} with the direction (if any) of every edge reversed. All other