diff --git a/arrays_strings/reverse_string/reverse_string_challenge.ipynb b/arrays_strings/reverse_string/reverse_string_challenge.ipynb
index a77aa6b..ebad367 100644
--- a/arrays_strings/reverse_string/reverse_string_challenge.ipynb
+++ b/arrays_strings/reverse_string/reverse_string_challenge.ipynb
@@ -78,9 +78,11 @@
    },
    "outputs": [],
    "source": [
-    "def reverse_string(list_chars):\n",
-    "    # TODO: Implement me\n",
-    "    pass"
+    "class ReverseString(object):\n",
+    "\n",
+    "    def reverse(self, chars):\n",
+    "        # TODO: Implement me\n",
+    "        pass"
    ]
   },
   {
@@ -113,25 +115,26 @@
     "\n",
     "class TestReverse(object):\n",
     "\n",
-    "    def test_reverse(self):\n",
-    "        assert_equal(reverse_string(None), None)\n",
-    "        assert_equal(reverse_string(['']), [''])\n",
-    "        assert_equal(reverse_string(\n",
+    "    def test_reverse(self, func):\n",
+    "        assert_equal(func(None), None)\n",
+    "        assert_equal(func(['']), [''])\n",
+    "        assert_equal(func(\n",
     "            ['f', 'o', 'o', ' ', 'b', 'a', 'r']),\n",
     "            ['r', 'a', 'b', ' ', 'o', 'o', 'f'])\n",
     "        print('Success: test_reverse')\n",
     "\n",
-    "    def test_reverse_inplace(self):\n",
+    "    def test_reverse_inplace(self, func):\n",
     "        target_list = ['f', 'o', 'o', ' ', 'b', 'a', 'r']\n",
-    "        reverse_string(target_list)\n",
+    "        func(target_list)\n",
     "        assert_equal(target_list, ['r', 'a', 'b', ' ', 'o', 'o', 'f'])\n",
     "        print('Success: test_reverse_inplace')\n",
     "\n",
     "\n",
     "def main():\n",
     "    test = TestReverse()\n",
-    "    test.test_reverse()\n",
-    "    test.test_reverse_inplace()\n",
+    "    reverse_string = ReverseString()\n",
+    "    test.test_reverse(reverse_string.reverse)\n",
+    "    test.test_reverse_inplace(reverse_string.reverse)\n",
     "\n",
     "\n",
     "if __name__ == '__main__':\n",
diff --git a/arrays_strings/reverse_string/reverse_string_solution.ipynb b/arrays_strings/reverse_string/reverse_string_solution.ipynb
index e3eb99b..112e6e2 100644
--- a/arrays_strings/reverse_string/reverse_string_solution.ipynb
+++ b/arrays_strings/reverse_string/reverse_string_solution.ipynb
@@ -94,14 +94,16 @@
     "from __future__ import division\n",
     "\n",
     "\n",
-    "def reverse_string(chars):\n",
-    "    if chars is None:\n",
-    "        return None\n",
-    "    size = len(chars)\n",
-    "    for i in range(size//2):\n",
-    "        chars[i], chars[size-1-i] = \\\n",
-    "            chars[size-1-i], chars[i]\n",
-    "    return chars"
+    "class ReverseString(object):\n",
+    "\n",
+    "    def reverse(self, chars):\n",
+    "        if chars is None:\n",
+    "            return None\n",
+    "        size = len(chars)\n",
+    "        for i in range(size//2):\n",
+    "            chars[i], chars[size-1-i] = \\\n",
+    "                chars[size-1-i], chars[i]\n",
+    "        return chars"
    ]
   },
   {
@@ -121,16 +123,17 @@
    },
    "outputs": [],
    "source": [
-    "def reverse_string_alt(string):\n",
-    "    if string is None:\n",
-    "        return None\n",
-    "    return string[::-1]\n",
+    "class ReverseStringAlt(object):\n",
     "\n",
+    "    def reverse_string_alt(string):\n",
+    "        if string is None:\n",
+    "            return None\n",
+    "        return string[::-1]\n",
     "\n",
-    "def reverse_string_alt2(string):\n",
-    "    if string is None:\n",
-    "        return None\n",
-    "    return ''.join(reversed(string))"
+    "    def reverse_string_alt2(string):\n",
+    "        if string is None:\n",
+    "            return None\n",
+    "        return ''.join(reversed(string))"
    ]
   },
   {
@@ -162,25 +165,26 @@
     "\n",
     "class TestReverse(object):\n",
     "\n",
-    "    def test_reverse(self):\n",
-    "        assert_equal(reverse_string(None), None)\n",
-    "        assert_equal(reverse_string(['']), [''])\n",
-    "        assert_equal(reverse_string(\n",
+    "    def test_reverse(self, func):\n",
+    "        assert_equal(func(None), None)\n",
+    "        assert_equal(func(['']), [''])\n",
+    "        assert_equal(func(\n",
     "            ['f', 'o', 'o', ' ', 'b', 'a', 'r']),\n",
     "            ['r', 'a', 'b', ' ', 'o', 'o', 'f'])\n",
     "        print('Success: test_reverse')\n",
     "\n",
-    "    def test_reverse_inplace(self):\n",
+    "    def test_reverse_inplace(self, func):\n",
     "        target_list = ['f', 'o', 'o', ' ', 'b', 'a', 'r']\n",
-    "        reverse_string(target_list)\n",
+    "        func(target_list)\n",
     "        assert_equal(target_list, ['r', 'a', 'b', ' ', 'o', 'o', 'f'])\n",
     "        print('Success: test_reverse_inplace')\n",
     "\n",
     "\n",
     "def main():\n",
     "    test = TestReverse()\n",
-    "    test.test_reverse()\n",
-    "    test.test_reverse_inplace()\n",
+    "    reverse_string = ReverseString()\n",
+    "    test.test_reverse(reverse_string.reverse)\n",
+    "    test.test_reverse_inplace(reverse_string.reverse)\n",
     "\n",
     "\n",
     "if __name__ == '__main__':\n",
diff --git a/arrays_strings/reverse_string/test_reverse_string.py b/arrays_strings/reverse_string/test_reverse_string.py
index cbb20f1..3f2a1f7 100644
--- a/arrays_strings/reverse_string/test_reverse_string.py
+++ b/arrays_strings/reverse_string/test_reverse_string.py
@@ -3,25 +3,26 @@ from nose.tools import assert_equal
 
 class TestReverse(object):
 
-    def test_reverse(self):
-        assert_equal(reverse_string(None), None)
-        assert_equal(reverse_string(['']), [''])
-        assert_equal(reverse_string(
+    def test_reverse(self, func):
+        assert_equal(func(None), None)
+        assert_equal(func(['']), [''])
+        assert_equal(func(
             ['f', 'o', 'o', ' ', 'b', 'a', 'r']),
             ['r', 'a', 'b', ' ', 'o', 'o', 'f'])
         print('Success: test_reverse')
 
-    def test_reverse_inplace(self):
+    def test_reverse_inplace(self, func):
         target_list = ['f', 'o', 'o', ' ', 'b', 'a', 'r']
-        reverse_string(target_list)
+        func(target_list)
         assert_equal(target_list, ['r', 'a', 'b', ' ', 'o', 'o', 'f'])
         print('Success: test_reverse_inplace')
 
 
 def main():
     test = TestReverse()
-    test.test_reverse()
-    test.test_reverse_inplace()
+    reverse_string = ReverseString()
+    test.test_reverse(reverse_string.reverse)
+    test.test_reverse_inplace(reverse_string.reverse)
 
 
 if __name__ == '__main__':