assertEqualCharNodes(traverser.depthFirstPostOrder('a'), "dbca");
    assertEqualCharNodes(traverser.depthFirstPostOrder('b'), "db");
    assertEqualCharNodes(traverser.depthFirstPostOrder('c'), "dbac");
    assertEqualCharNodes(traverser.depthFirstPostOrder('d'), "d");
  }

  @Test
  public void forGraph_depthFirstPostOrderIterable_multigraph() {

    assertEqualCharNodes(traverser.depthFirstPostOrder('a'), "dbca");
    assertEqualCharNodes(traverser.depthFirstPostOrder('b'), "db");
    assertEqualCharNodes(traverser.depthFirstPostOrder('c'), "dbac");
    assertEqualCharNodes(traverser.depthFirstPostOrder('d'), "d");
  }

  @Test
  public void forGraph_depthFirstPostOrderIterable_multigraph() {

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            });
        }
        URL website = new URL(urlString);
        ReadableByteChannel rbc;
        rbc = Channels.newChannel(website.openStream());
        FileOutputStream fos = new FileOutputStream(destination);
        fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
        fos.close();
        rbc.close();
    }