Iterable<Character> result = Traverser.forGraph(TWO_TREES).depthFirstPostOrder('a');

    assertEqualCharNodes(result, "ba");
  }

  @Test
  public void forGraph_depthFirstPostOrderIterable_twoTrees() {
    assertEqualCharNodes(
        Traverser.forGraph(TWO_TREES).depthFirstPostOrder(charactersOf("a")), "ba");
    assertEqualCharNodes(
        Traverser.forGraph(TWO_TREES).depthFirstPostOrder(charactersOf("ac")), "badc");
  }

        map.put("デュ", new String[] { "dyu" });
        map.put("トゥ", new String[] { "tu", "twu" });
        map.put("ドゥ", new String[] { "du", "dwu" });

        map.put("バ", new String[] { "ba" });
        map.put("ビ", new String[] { "bi" });
        map.put("ブ", new String[] { "bu" });
        map.put("ベ", new String[] { "be" });
        map.put("ボ", new String[] { "bo" });