      "        root.insert(1)\n",
      "        root.insert(3)\n",
      "\n",
      "        with captured_output() as (out, err):\n",
      "            root.in_order_traversal(sys.stdout.write)\n",
      "            assert_equal(out.getvalue().strip(), '12358')\n",
      "\n",
      "        with captured_output() as (out, err):\n",
      "            root.pre_order_traversal(sys.stdout.write)\n",
      "            assert_equal(out.getvalue().strip(), '52138')\n",
 
</s> remove     "            root.in_order_traversal(sys.stdout.write)\n",
 </s> add     "            in_order_traversal(node, sys.stdout.write)\n", </s> remove     "            root.pre_order_traversal(sys.stdout.write)\n",
 </s> add     "            pre_order_traversal(node, sys.stdout.write)\n", </s> remove     "            root.pre_order_traversal(sys.stdout.write)\n",
 </s> add     "            pre_order_traversal(node, sys.stdout.write)\n", </s> remove     "            root.post_order_traversal(sys.stdout.write)\n",
 </s> add     "            post_order_traversal(node, sys.stdout.write)\n", </s> remove     "            root.post_order_traversal(sys.stdout.write)\n",
 </s> add     "            post_order_traversal(node, sys.stdout.write)\n",
    "            in_order_traversal(node, sys.stdout.write)\n",
      "        root.insert(1)\n",
      "        root.insert(3)\n",
      "\n",
      "        with captured_output() as (out, err):\n",
    "            in_order_traversal(node, sys.stdout.write)\n",
      "            assert_equal(out.getvalue().strip(), '12358')\n",
      "\n",
      "        with captured_output() as (out, err):\n",
      "            root.pre_order_traversal(sys.stdout.write)\n",
      "            assert_equal(out.getvalue().strip(), '52138')\n",
keep keep keep keep replace keep keep keep keep keep
 Simpilfied depth first search challenge. 
graphs_trees/tree_dfs/dfs_challenge.ipynb