diff --git a/graphs_trees/bst_validate/bst_validate_challenge.ipynb b/graphs_trees/bst_validate/bst_validate_challenge.ipynb
index c5e579a..5aef392 100644
--- a/graphs_trees/bst_validate/bst_validate_challenge.ipynb
+++ b/graphs_trees/bst_validate/bst_validate_challenge.ipynb
@@ -103,9 +103,11 @@
    },
    "outputs": [],
    "source": [
-    "def validate_bst(node):\n",
-    "    # TODO: Implement me\n",
-    "    pass"
+    "class BstValidate(Bst):\n",
+    "\n",
+    "    def validate(self):\n",
+    "        # TODO: Implement me\n",
+    "        pass"
    ]
   },
   {
@@ -142,22 +144,22 @@
     "        validate_bst(None)\n",
     "\n",
     "    def test_bst_validate(self):\n",
-    "        node = Node(5)\n",
-    "        insert(node, 8)\n",
-    "        insert(node, 5)\n",
-    "        insert(node, 6)\n",
-    "        insert(node, 4)\n",
-    "        insert(node, 7)\n",
-    "        assert_equal(validate_bst(node), True)\n",
+    "        bst = BstValidate(Node(5))\n",
+    "        bst.insert(8)\n",
+    "        bst.insert(5)\n",
+    "        bst.insert(6)\n",
+    "        bst.insert(4)\n",
+    "        bst.insert(7)\n",
+    "        assert_equal(bst.validate(), True)\n",
     "\n",
-    "        root = Node(5)\n",
+    "        bst = BstValidate(Node(5))\n",
     "        left = Node(5)\n",
     "        right = Node(8)\n",
     "        invalid = Node(20)\n",
-    "        root.left = left\n",
-    "        root.right = right\n",
-    "        root.left.right = invalid\n",
-    "        assert_equal(validate_bst(root), False)\n",
+    "        bst.root.left = left\n",
+    "        bst.root.right = right\n",
+    "        bst.root.left.right = invalid\n",
+    "        assert_equal(bst.validate(), False)\n",
     "\n",
     "        print('Success: test_bst_validate')\n",
     "\n",
diff --git a/graphs_trees/bst_validate/bst_validate_solution.ipynb b/graphs_trees/bst_validate/bst_validate_solution.ipynb
index 23f50c2..3b3dd7b 100644
--- a/graphs_trees/bst_validate/bst_validate_solution.ipynb
+++ b/graphs_trees/bst_validate/bst_validate_solution.ipynb
@@ -113,24 +113,26 @@
    },
    "outputs": [],
    "source": [
-    "def validate_bst(node):\n",
-    "    if node is None:\n",
-    "        raise Exception('No root node')\n",
-    "    return _validate_bst(node, None, None)\n",
+    "import sys\n",
     "\n",
     "\n",
-    "def _validate_bst(node, mininum, maximum):\n",
-    "    if node is None:\n",
-    "        return True\n",
-    "    if mininum is not None and node.data <= mininum:\n",
-    "        return False\n",
-    "    if maximum is not None and node.data > maximum:\n",
-    "        return False\n",
-    "    if not _validate_bst(node.left, mininum, node.data):\n",
-    "        return False\n",
-    "    if not _validate_bst(node.right, node.data, maximum):\n",
-    "        return False\n",
-    "    return True"
+    "class BstValidate(Bst):\n",
+    "\n",
+    "    def validate(self):\n",
+    "        if self.root is None:\n",
+    "            raise Exception('No root node')\n",
+    "        return self._validate(self.root)\n",
+    "\n",
+    "    def _validate(self, node, mininum=-sys.maxsize, maximum=sys.maxsize):\n",
+    "        if node is None:\n",
+    "            return True\n",
+    "        if node.data <= mininum or node.data > maximum:\n",
+    "            return False\n",
+    "        if not self._validate(node.left, mininum, node.data):\n",
+    "            return False\n",
+    "        if not self._validate(node.right, node.data, maximum):\n",
+    "            return False\n",
+    "        return True"
    ]
   },
   {
@@ -168,22 +170,22 @@
     "        validate_bst(None)\n",
     "\n",
     "    def test_bst_validate(self):\n",
-    "        node = Node(5)\n",
-    "        insert(node, 8)\n",
-    "        insert(node, 5)\n",
-    "        insert(node, 6)\n",
-    "        insert(node, 4)\n",
-    "        insert(node, 7)\n",
-    "        assert_equal(validate_bst(node), True)\n",
+    "        bst = BstValidate(Node(5))\n",
+    "        bst.insert(8)\n",
+    "        bst.insert(5)\n",
+    "        bst.insert(6)\n",
+    "        bst.insert(4)\n",
+    "        bst.insert(7)\n",
+    "        assert_equal(bst.validate(), True)\n",
     "\n",
-    "        root = Node(5)\n",
+    "        bst = BstValidate(Node(5))\n",
     "        left = Node(5)\n",
     "        right = Node(8)\n",
     "        invalid = Node(20)\n",
-    "        root.left = left\n",
-    "        root.right = right\n",
-    "        root.left.right = invalid\n",
-    "        assert_equal(validate_bst(root), False)\n",
+    "        bst.root.left = left\n",
+    "        bst.root.right = right\n",
+    "        bst.root.left.right = invalid\n",
+    "        assert_equal(bst.validate(), False)\n",
     "\n",
     "        print('Success: test_bst_validate')\n",
     "\n",
diff --git a/graphs_trees/bst_validate/test_bst_validate.py b/graphs_trees/bst_validate/test_bst_validate.py
index 815a03e..89a9dcb 100644
--- a/graphs_trees/bst_validate/test_bst_validate.py
+++ b/graphs_trees/bst_validate/test_bst_validate.py
@@ -9,22 +9,22 @@ class TestBstValidate(object):
         validate_bst(None)
 
     def test_bst_validate(self):
-        node = Node(5)
-        insert(node, 8)
-        insert(node, 5)
-        insert(node, 6)
-        insert(node, 4)
-        insert(node, 7)
-        assert_equal(validate_bst(node), True)
+        bst = BstValidate(Node(5))
+        bst.insert(8)
+        bst.insert(5)
+        bst.insert(6)
+        bst.insert(4)
+        bst.insert(7)
+        assert_equal(bst.validate(), True)
 
-        root = Node(5)
+        bst = BstValidate(Node(5))
         left = Node(5)
         right = Node(8)
         invalid = Node(20)
-        root.left = left
-        root.right = right
-        root.left.right = invalid
-        assert_equal(validate_bst(root), False)
+        bst.root.left = left
+        bst.root.right = right
+        bst.root.left.right = invalid
+        assert_equal(bst.validate(), False)
 
         print('Success: test_bst_validate')