diff --git a/graphs_trees/tree_dfs/dfs_challenge.ipynb b/graphs_trees/tree_dfs/dfs_challenge.ipynb
index 6125431..5ec8d15 100644
--- a/graphs_trees/tree_dfs/dfs_challenge.ipynb
+++ b/graphs_trees/tree_dfs/dfs_challenge.ipynb
@@ -97,12 +97,15 @@
    "source": [
     "def in_order_traversal(node, visit_func):\n",
     "    # TODO: Implement me\n",
+    "    pass\n",
     "\n",
     "def pre_order_traversal(node, visit_func):\n",
     "    # TODO: Implement me\n",
+    "    pass\n",
     "\n",
     "def post_order_traversal(node, visit_func):\n",
-    "    # TODO: Implement me"
+    "    # TODO: Implement me\n",
+    "    pass"
    ]
   },
   {
@@ -120,7 +123,7 @@
    },
    "outputs": [],
    "source": [
-    "%run ../utils/captured_output.py"
+    "%run ../utils/results.py"
    ]
   },
   {
@@ -132,12 +135,14 @@
    "outputs": [],
    "source": [
     "# %load test_dfs.py\n",
-    "from __future__ import print_function\n",
     "from nose.tools import assert_equal\n",
     "\n",
     "\n",
     "class TestDfs(object):\n",
     "\n",
+    "    def __init__(self):\n",
+    "        self.results = Results()\n",
+    "\n",
     "    def test_dfs(self):\n",
     "        node = Node(5)\n",
     "        insert(node, 2)\n",
@@ -145,17 +150,17 @@
     "        insert(node, 1)\n",
     "        insert(node, 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",
+    "        in_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[1, 2, 3, 5, 8]\")\n",
+    "        self.results.clear_results()\n",
     "\n",
-    "        with captured_output() as (out, err):\n",
-    "            pre_order_traversal(node, sys.stdout.write)\n",
-    "            assert_equal(out.getvalue().strip(), '52138')\n",
+    "        pre_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[5, 2, 1, 3, 8]\")\n",
+    "        self.results.clear_results()\n",
     "\n",
-    "        with captured_output() as (out, err):\n",
-    "            post_order_traversal(node, sys.stdout.write)\n",
-    "            assert_equal(out.getvalue().strip(), '13285')\n",
+    "        post_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[1, 3, 2, 8, 5]\")\n",
+    "        self.results.clear_results()\n",
     "\n",
     "        node = Node(1)\n",
     "        insert(node, 2)\n",
@@ -163,17 +168,16 @@
     "        insert(node, 4)\n",
     "        insert(node, 5)\n",
     "\n",
-    "        with captured_output() as (out, err):\n",
-    "            in_order_traversal(node, sys.stdout.write)\n",
-    "            assert_equal(out.getvalue().strip(), '12345')\n",
+    "        in_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[1, 2, 3, 4, 5]\")\n",
+    "        self.results.clear_results()\n",
     "\n",
-    "        with captured_output() as (out, err):\n",
-    "            pre_order_traversal(node, sys.stdout.write)\n",
-    "            assert_equal(out.getvalue().strip(), '12345')\n",
+    "        pre_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[1, 2, 3, 4, 5]\")\n",
+    "        self.results.clear_results()\n",
     "\n",
-    "        with captured_output() as (out, err):\n",
-    "            post_order_traversal(node, sys.stdout.write)\n",
-    "            assert_equal(out.getvalue().strip(), '54321')\n",
+    "        post_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[5, 4, 3, 2, 1]\")\n",
     "\n",
     "        print('Success: test_dfs')\n",
     "\n",
diff --git a/graphs_trees/tree_dfs/dfs_solution.ipynb b/graphs_trees/tree_dfs/dfs_solution.ipynb
index bdb6380..22ff845 100644
--- a/graphs_trees/tree_dfs/dfs_solution.ipynb
+++ b/graphs_trees/tree_dfs/dfs_solution.ipynb
@@ -163,11 +163,11 @@
    "cell_type": "code",
    "execution_count": 3,
    "metadata": {
-    "collapsed": false
+    "collapsed": true
    },
    "outputs": [],
    "source": [
-    "%run ../utils/captured_output.py"
+    "%run ../utils/results.py"
    ]
   },
   {
@@ -187,12 +187,14 @@
    ],
    "source": [
     "%%writefile test_dfs.py\n",
-    "from __future__ import print_function\n",
     "from nose.tools import assert_equal\n",
     "\n",
     "\n",
     "class TestDfs(object):\n",
     "\n",
+    "    def __init__(self):\n",
+    "        self.results = Results()\n",
+    "\n",
     "    def test_dfs(self):\n",
     "        node = Node(5)\n",
     "        insert(node, 2)\n",
@@ -200,17 +202,17 @@
     "        insert(node, 1)\n",
     "        insert(node, 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",
+    "        in_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[1, 2, 3, 5, 8]\")\n",
+    "        self.results.clear_results()\n",
     "\n",
-    "        with captured_output() as (out, err):\n",
-    "            pre_order_traversal(node, sys.stdout.write)\n",
-    "            assert_equal(out.getvalue().strip(), '52138')\n",
+    "        pre_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[5, 2, 1, 3, 8]\")\n",
+    "        self.results.clear_results()\n",
     "\n",
-    "        with captured_output() as (out, err):\n",
-    "            post_order_traversal(node, sys.stdout.write)\n",
-    "            assert_equal(out.getvalue().strip(), '13285')\n",
+    "        post_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[1, 3, 2, 8, 5]\")\n",
+    "        self.results.clear_results()\n",
     "\n",
     "        node = Node(1)\n",
     "        insert(node, 2)\n",
@@ -218,17 +220,16 @@
     "        insert(node, 4)\n",
     "        insert(node, 5)\n",
     "\n",
-    "        with captured_output() as (out, err):\n",
-    "            in_order_traversal(node, sys.stdout.write)\n",
-    "            assert_equal(out.getvalue().strip(), '12345')\n",
+    "        in_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[1, 2, 3, 4, 5]\")\n",
+    "        self.results.clear_results()\n",
     "\n",
-    "        with captured_output() as (out, err):\n",
-    "            pre_order_traversal(node, sys.stdout.write)\n",
-    "            assert_equal(out.getvalue().strip(), '12345')\n",
+    "        pre_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[1, 2, 3, 4, 5]\")\n",
+    "        self.results.clear_results()\n",
     "\n",
-    "        with captured_output() as (out, err):\n",
-    "            post_order_traversal(node, sys.stdout.write)\n",
-    "            assert_equal(out.getvalue().strip(), '54321')\n",
+    "        post_order_traversal(node, self.results.add_result)\n",
+    "        assert_equal(str(self.results), \"[5, 4, 3, 2, 1]\")\n",
     "\n",
     "        print('Success: test_dfs')\n",
     "\n",
diff --git a/graphs_trees/tree_dfs/test_dfs.py b/graphs_trees/tree_dfs/test_dfs.py
index 44397e1..f2c1f94 100644
--- a/graphs_trees/tree_dfs/test_dfs.py
+++ b/graphs_trees/tree_dfs/test_dfs.py
@@ -1,9 +1,11 @@
-from __future__ import print_function
 from nose.tools import assert_equal
 
 
 class TestDfs(object):
 
+    def __init__(self):
+        self.results = Results()
+
     def test_dfs(self):
         node = Node(5)
         insert(node, 2)
@@ -11,17 +13,17 @@ class TestDfs(object):
         insert(node, 1)
         insert(node, 3)
 
-        with captured_output() as (out, err):
-            in_order_traversal(node, sys.stdout.write)
-            assert_equal(out.getvalue().strip(), '12358')
+        in_order_traversal(node, self.results.add_result)
+        assert_equal(str(self.results), "[1, 2, 3, 5, 8]")
+        self.results.clear_results()
 
-        with captured_output() as (out, err):
-            pre_order_traversal(node, sys.stdout.write)
-            assert_equal(out.getvalue().strip(), '52138')
+        pre_order_traversal(node, self.results.add_result)
+        assert_equal(str(self.results), "[5, 2, 1, 3, 8]")
+        self.results.clear_results()
 
-        with captured_output() as (out, err):
-            post_order_traversal(node, sys.stdout.write)
-            assert_equal(out.getvalue().strip(), '13285')
+        post_order_traversal(node, self.results.add_result)
+        assert_equal(str(self.results), "[1, 3, 2, 8, 5]")
+        self.results.clear_results()
 
         node = Node(1)
         insert(node, 2)
@@ -29,17 +31,16 @@ class TestDfs(object):
         insert(node, 4)
         insert(node, 5)
 
-        with captured_output() as (out, err):
-            in_order_traversal(node, sys.stdout.write)
-            assert_equal(out.getvalue().strip(), '12345')
+        in_order_traversal(node, self.results.add_result)
+        assert_equal(str(self.results), "[1, 2, 3, 4, 5]")
+        self.results.clear_results()
 
-        with captured_output() as (out, err):
-            pre_order_traversal(node, sys.stdout.write)
-            assert_equal(out.getvalue().strip(), '12345')
+        pre_order_traversal(node, self.results.add_result)
+        assert_equal(str(self.results), "[1, 2, 3, 4, 5]")
+        self.results.clear_results()
 
-        with captured_output() as (out, err):
-            post_order_traversal(node, sys.stdout.write)
-            assert_equal(out.getvalue().strip(), '54321')
+        post_order_traversal(node, self.results.add_result)
+        assert_equal(str(self.results), "[5, 4, 3, 2, 1]")
 
         print('Success: test_dfs')