diff --git a/graphs_trees/bst_min/bst_min_challenge.ipynb b/graphs_trees/bst_min/bst_min_challenge.ipynb
index 9ec1945..52e76d5 100644
--- a/graphs_trees/bst_min/bst_min_challenge.ipynb
+++ b/graphs_trees/bst_min/bst_min_challenge.ipynb
@@ -39,6 +39,8 @@
     "* Are the array elements unique?\n",
     "    * Yes\n",
     "* Can we assume we already have a Node class with an insert method?\n",
+    "    * Yes\n",
+    "* Can we assume this fits memory?\n",
     "    * Yes"
    ]
   },
@@ -90,11 +92,11 @@
    "source": [
     "def create_min_bst(array):\n",
     "    # TODO: Implement me\n",
-    "    # Calls __create_min_bst__\n",
+    "    # Calls _create_min_bst\n",
     "    pass    \n",
     "\n",
     "\n",
-    "def __create_min_bst__(array, start, end):\n",
+    "def _create_min_bst(array, start, end):\n",
     "    # TODO: Implement me\n",
     "    pass"
    ]
@@ -171,21 +173,21 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 2",
+   "display_name": "Python 3",
    "language": "python",
-   "name": "python2"
+   "name": "python3"
   },
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 2
+    "version": 3
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "pygments_lexer": "ipython3",
+   "version": "3.5.0"
   }
  },
  "nbformat": 4,
diff --git a/graphs_trees/bst_min/bst_min_solution.ipynb b/graphs_trees/bst_min/bst_min_solution.ipynb
index 228fe95..b4b97cc 100644
--- a/graphs_trees/bst_min/bst_min_solution.ipynb
+++ b/graphs_trees/bst_min/bst_min_solution.ipynb
@@ -38,6 +38,8 @@
     "* Are the array elements unique?\n",
     "    * Yes\n",
     "* Can we assume we already have a Node class with an insert method?\n",
+    "    * Yes\n",
+    "* Can we assume this fits memory?\n",
     "    * Yes"
    ]
   },
@@ -103,16 +105,16 @@
     "def create_min_bst(array):\n",
     "    if array is None:\n",
     "        return\n",
-    "    return __create_min_bst__(array, 0, len(array)-1)\n",
+    "    return _create_min_bst(array, 0, len(array)-1)\n",
     "\n",
     "\n",
-    "def __create_min_bst__(array, start, end):\n",
+    "def _create_min_bst(array, start, end):\n",
     "    if end < start:\n",
-    "        return\n",
+    "        return None\n",
     "    mid = (start + end) // 2\n",
     "    node = Node(array[mid])\n",
-    "    node.left = __create_min_bst__(array, start, mid-1)\n",
-    "    node.right = __create_min_bst__(array, mid+1, end)\n",
+    "    node.left = _create_min_bst(array, start, mid-1)\n",
+    "    node.right = _create_min_bst(array, mid+1, end)\n",
     "    return node"
    ]
   },
@@ -199,21 +201,21 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 2",
+   "display_name": "Python 3",
    "language": "python",
-   "name": "python2"
+   "name": "python3"
   },
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 2
+    "version": 3
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "pygments_lexer": "ipython3",
+   "version": "3.5.0"
   }
  },
  "nbformat": 4,