diff --git a/linked-lists/delete-mid.ipynb b/linked-lists/delete-mid.ipynb
index dfd6266..f63ffd9 100644
--- a/linked-lists/delete-mid.ipynb
+++ b/linked-lists/delete-mid.ipynb
@@ -19,8 +19,6 @@
    "source": [
     "## Clarifying Questions\n",
     "\n",
-    "* Do we assume the linked list class already exists?\n",
-    "    * No, create one\n",
     "* What if the final node is being deleted, for example a single node list?\n",
     "    * Make it a dummy node"
    ]
@@ -61,6 +59,17 @@
     "## Code"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "%run linked_list.py"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -74,10 +83,7 @@
     "        self.data = data\n",
     "        self.next = None\n",
     "\n",
-    "class LinkedList(object):\n",
-    "    def __init__(self, head):\n",
-    "        self.head = head\n",
-    "        \n",
+    "class MyLinkedList(LinkedList):\n",
     "    def delete_node(self, node):\n",
     "        if self.head is None:\n",
     "            return\n",
@@ -89,25 +95,7 @@
     "            node.next = None\n",
     "        else:\n",
     "            node.data = next.data\n",
-    "            node.next = next.next\n",
-    "\n",
-    "        \n",
-    "    def insert_to_front(self, data):\n",
-    "        if data is None:\n",
-    "            return\n",
-    "        node = Node(data)\n",
-    "        if self.head is None:\n",
-    "            self.head = node\n",
-    "        else:\n",
-    "            node.next = self.head\n",
-    "            self.head = node\n",
-    "        return node\n",
-    "            \n",
-    "    def print_list(self):\n",
-    "        curr_node = self.head\n",
-    "        while curr_node is not None:\n",
-    "            print(curr_node.data)\n",
-    "            curr_node = curr_node.next"
+    "            node.next = next.next"
    ]
   },
   {
diff --git a/linked-lists/kth-to-last-elem.ipynb b/linked-lists/kth-to-last-elem.ipynb
index f064e44..99b32cc 100644
--- a/linked-lists/kth-to-last-elem.ipynb
+++ b/linked-lists/kth-to-last-elem.ipynb
@@ -18,17 +18,13 @@
    "source": [
     "## Clarifying Questions\n",
     "\n",
-    "* Do we assume the linked list class already exists?\n",
-    "    * No, create one\n",
     "* Is k an integer?\n",
     "    * Yes\n",
     "* If k = 0, does this return the last element?\n",
     "    * Yes\n",
     "* What happens if k is greater than or equal to the length of the linked list?\n",
     "    * Return None\n",
-    "* Can you insert NULL values in the list?\n",
-    "    * No\n",
-    "* Can use additional data structures?\n",
+    "* Can you use additional data structures?\n",
     "    * No"
    ]
   },
@@ -69,6 +65,17 @@
     "## Code"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "%run linked_list.py"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -77,28 +84,12 @@
    },
    "outputs": [],
    "source": [
-    "class Node(object):\n",
-    "    def __init__(self, data):\n",
-    "        self.data = data\n",
-    "        self.next = None\n",
-    "        \n",
-    "class LinkedList(object):\n",
-    "    def __init__(self, head):\n",
-    "        self.head = head\n",
-    "        \n",
-    "    def __len__(self):\n",
-    "        curr = self.head\n",
-    "        counter = 0\n",
-    "        while curr is not None:\n",
-    "            counter += 1\n",
-    "            curr = curr.next\n",
-    "        return counter\n",
-    "        \n",
+    "class MyLinkedList(LinkedList):\n",
     "    def kth_to_last_elem(self, k):\n",
     "        if self.head is None:\n",
     "            return\n",
     "        if type(k) != int:\n",
-    "            return\n",
+    "            raise ValueError('')\n",
     "        if k >= len(self):\n",
     "            return\n",
     "        curr = self.head\n",
@@ -112,20 +103,19 @@
     "        while curr.next is not None:\n",
     "            curr = curr.next\n",
     "            prev = prev.next\n",
-    "        return prev.data\n",
-    "        \n",
-    "    def insert_to_front(self, data):\n",
-    "        if data is None:\n",
-    "            return\n",
-    "        node = Node(data)\n",
-    "        if self.head is None:\n",
-    "            self.head = node\n",
-    "        else:\n",
-    "            node.next = self.head\n",
-    "            self.head = node\n",
-    "            \n",
+    "        return prev.data"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
     "# Empty list\n",
-    "linked_list = LinkedList(None)\n",
+    "linked_list = MyLinkedList(None)\n",
     "print(linked_list.kth_to_last_elem(0))\n",
     "# k is not an integer\n",
     "print(linked_list.kth_to_last_elem('a'))\n",
@@ -133,7 +123,7 @@
     "print(linked_list.kth_to_last_elem(100))\n",
     "# One element, k = 0\n",
     "head = Node(2)\n",
-    "linked_list = LinkedList(head)\n",
+    "linked_list = MyLinkedList(head)\n",
     "print(linked_list.kth_to_last_elem(0))\n",
     "# General case with many elements, k < length of linked list\n",
     "linked_list.insert_to_front(1)\n",
diff --git a/linked-lists/remove-duplicates.ipynb b/linked-lists/remove-duplicates.ipynb
index 96e5863..cc716a5 100644
--- a/linked-lists/remove-duplicates.ipynb
+++ b/linked-lists/remove-duplicates.ipynb
@@ -20,13 +20,11 @@
    "source": [
     "## Clarifying Questions\n",
     "\n",
-    "* Do we assume the linked list class already exists?\n",
-    "    * No, create one\n",
     "* Is this a singly or doubly linked list?\n",
     "    * Singly\n",
     "* Can you insert NULL values in the list?\n",
     "    * No\n",
-    "* Can use additional data structures?\n",
+    "* Can you use additional data structures?\n",
     "    * Implement both solutions"
    ]
   },
@@ -70,6 +68,17 @@
     "## Code: Hash Map Lookup"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "%run linked_list.py"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -78,15 +87,7 @@
    },
    "outputs": [],
    "source": [
-    "class Node(object):\n",
-    "    def __init__(self, data):\n",
-    "        self.next = None\n",
-    "        self.data = data\n",
-    "\n",
-    "class LinkedList(object):\n",
-    "    def __init__(self, head):\n",
-    "        self.head = head\n",
-    "        \n",
+    "class MyLinkedList(LinkedList):\n",
     "    def remove_dupes(self):\n",
     "        seen_data = set()\n",
     "        curr = self.head\n",
@@ -97,31 +98,24 @@
     "            else:\n",
     "                seen_data.add(curr.data)\n",
     "                prev = curr\n",
-    "            curr = curr.next\n",
-    "            \n",
-    "    def insert_to_front(self, data):\n",
-    "        if data is None:\n",
-    "            return\n",
-    "        node = Node(data)\n",
-    "        if self.head is None:\n",
-    "            self.head = node\n",
-    "        else:\n",
-    "            node.next = self.head\n",
-    "            self.head = node            \n",
-    "            \n",
-    "    def print_list(self):\n",
-    "        curr = self.head\n",
-    "        while curr is not None:\n",
-    "            print(curr.data)\n",
-    "            curr = curr.next\n",
-    "            \n",
+    "            curr = curr.next"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
     "# Empty linked list\n",
-    "linked_list = LinkedList(None)\n",
+    "linked_list = MyLinkedList(None)\n",
     "linked_list.remove_dupes()\n",
     "linked_list.print_list()\n",
     "# One element linked list\n",
     "head = Node(2)\n",
-    "linked_list = LinkedList(head)\n",
+    "linked_list = MyLinkedList(head)\n",
     "linked_list.remove_dupes()\n",
     "linked_list.print_list()\n",
     "# Multiple elements\n",
@@ -174,14 +168,7 @@
    },
    "outputs": [],
    "source": [
-    "class Node(object):\n",
-    "    def __init__(self, data):\n",
-    "        self.next = None\n",
-    "        self.data = data\n",
-    "\n",
-    "class LinkedList(object):\n",
-    "    def __init__(self, head):\n",
-    "        self.head = head\n",
+    "class MyLinkedList(LinkedList):\n",
     "        \n",
     "    def remove_dupes(self):\n",
     "        curr = self.head\n",
@@ -192,31 +179,24 @@
     "                    runner.next = runner.next.next\n",
     "                else:\n",
     "                    runner = runner.next\n",
-    "            curr = curr.next\n",
-    "                                \n",
-    "    def insert_to_front(self, data):\n",
-    "        if data is None:\n",
-    "            return\n",
-    "        node = Node(data)\n",
-    "        if self.head is None:\n",
-    "            self.head = node\n",
-    "        else:\n",
-    "            node.next = self.head\n",
-    "            self.head = node            \n",
-    "            \n",
-    "    def print_list(self):\n",
-    "        curr = self.head\n",
-    "        while curr is not None:\n",
-    "            print(curr.data)\n",
-    "            curr = curr.next\n",
-    "            \n",
+    "            curr = curr.next"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
     "# Empty linked list\n",
-    "linked_list = LinkedList(None)\n",
+    "linked_list = MyLinkedList(None)\n",
     "linked_list.remove_dupes()\n",
     "linked_list.print_list()\n",
     "# One element linked list\n",
     "head = Node(2)\n",
-    "linked_list = LinkedList(head)\n",
+    "linked_list = MyLinkedList(head)\n",
     "linked_list.remove_dupes()\n",
     "linked_list.print_list()\n",
     "# Multiple elements\n",