diff --git a/linked-lists/linked-list.ipynb b/linked-lists/linked-list.ipynb
index bd508ef..f640629 100644
--- a/linked-lists/linked-list.ipynb
+++ b/linked-lists/linked-list.ipynb
@@ -13,17 +13,20 @@
    "source": [
     "## Problem: Implement a linked list with insert, append, find, delete, length, and print methods\n",
     "\n",
-    "* [Clarifying Questions](#Clarifying-Questions)\n",
+    "* [Constraints and Assumptions](#Constraints-and-Assumptions)\n",
     "* [Test Cases](#Test-Cases)\n",
     "* [Algorithm](#Algorithm)\n",
-    "* [Code](#Code)"
+    "* [Code](#Code)\n",
+    "* [Unit Test](#Unit-Test)"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Clarifying Questions\n",
+    "## Constraints and Assumptions\n",
+    "\n",
+    "*Problem statements are often intentionally ambiguous.  Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
     "\n",
     "* Is this a singly or doubly linked list?\n",
     "    * Singly\n",
@@ -163,11 +166,19 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 1,
    "metadata": {
     "collapsed": false
    },
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Overwriting linked_list.py\n"
+     ]
+    }
+   ],
    "source": [
     "%%writefile linked_list.py\n",
     "\n",
@@ -200,6 +211,7 @@
     "        else:\n",
     "            node.next = self.head\n",
     "            self.head = node\n",
+    "        return node\n",
     "            \n",
     "    def append(self, data, next_node=None):\n",
     "        if data is None:\n",
@@ -212,6 +224,7 @@
     "            while curr_node.next is not None:\n",
     "                curr_node = curr_node.next\n",
     "            curr_node.next = node\n",
+    "        return node\n",
     "            \n",
     "    def find(self, data):\n",
     "        if data is None:\n",
@@ -224,6 +237,7 @@
     "                return curr_node\n",
     "            else:\n",
     "                curr_node = curr_node.next\n",
+    "        return\n",
     "                \n",
     "    def delete(self, data):\n",
     "        if data is None:\n",
@@ -244,14 +258,22 @@
     "        curr_node = self.head\n",
     "        while curr_node is not None:\n",
     "            print(curr_node.data)\n",
-    "            curr_node = curr_node.next"
+    "            curr_node = curr_node.next\n",
+    "\n",
+    "    def get_all_data(self):\n",
+    "        data = []\n",
+    "        curr_node = self.head\n",
+    "        while curr_node is not None:\n",
+    "            data.append(curr_node.data)\n",
+    "            curr_node = curr_node.next\n",
+    "        return data"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 2,
    "metadata": {
-    "collapsed": true
+    "collapsed": false
    },
    "outputs": [],
    "source": [
@@ -259,139 +281,170 @@
    ]
   },
   {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {
-    "collapsed": false
-   },
-   "outputs": [],
+   "cell_type": "markdown",
+   "metadata": {},
    "source": [
-    "# Test insert_to_front\n",
-    "# Insert in an empty list\n",
-    "linked_list = LinkedList(None)\n",
-    "linked_list.insert_to_front(10)\n",
-    "linked_list.print_list()\n",
-    "# Insert a NULL\n",
-    "linked_list.insert_to_front(None)\n",
-    "linked_list.print_list()\n",
-    "# Insert in a list with one element or more elements\n",
-    "linked_list.insert_to_front('a')\n",
-    "linked_list.insert_to_front('bc')\n",
-    "linked_list.print_list()"
+    "## Unit Test"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "*It is important to identify and run through general and edge cases from the [Test Cases](#Test-Cases) section by hand.  You generally will not be asked to write a unit test like what is shown below.*"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 3,
    "metadata": {
     "collapsed": false
    },
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Test: insert_to_front on an empty list\n",
+      "Test: insert_to_front on a NULL\n",
+      "Test: insert_to_front general case\n",
+      "Success: test_insert_to_front\n",
+      "\n",
+      "Test: append on an empty list\n",
+      "Test: append a NULL\n",
+      "Test: append general case\n",
+      "Success: test_append\n",
+      "\n",
+      "Test: find on an empty list\n",
+      "Test: find a NULL\n",
+      "Test: find general case with matches\n",
+      "Test: find general case with no matches\n",
+      "Success: test_find\n",
+      "\n",
+      "Test: delete on an empty list\n",
+      "Test: delete a NULL\n",
+      "Test: delete general case with matches\n",
+      "Test: delete general case with no matches\n",
+      "Success: test_delete\n",
+      "\n",
+      "Test: len on an empty list\n",
+      "Test: len general case\n",
+      "Success: test_len\n",
+      "\n"
+     ]
+    }
+   ],
    "source": [
-    "# Test append\n",
-    "# Insert in an empty list\n",
-    "linked_list = LinkedList(None)\n",
-    "linked_list.append(10)\n",
-    "linked_list.print_list()\n",
-    "# Insert a NULL\n",
-    "linked_list.append(None)\n",
-    "linked_list.print_list()\n",
-    "# Insert in a list with one element or more elements\n",
-    "linked_list.append('a')\n",
-    "linked_list.append('bc')\n",
-    "linked_list.print_list()"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {
-    "collapsed": false
-   },
-   "outputs": [],
-   "source": [
-    "# Test find\n",
-    "# Find in an empty list\n",
-    "linked_list = LinkedList(None)\n",
-    "node = linked_list.find('a')\n",
-    "print(node)\n",
-    "# Find a NULL\n",
-    "head = Node(10)\n",
-    "linked_list = LinkedList(head)\n",
-    "node = linked_list.find(None)\n",
-    "print(node)\n",
-    "# Find in a list with one element or more matching elements\n",
-    "head = Node(10)\n",
-    "linked_list = LinkedList(head)\n",
-    "linked_list.insert_to_front('a')\n",
-    "linked_list.insert_to_front('bc')\n",
-    "node = linked_list.find('a')\n",
-    "print(node)\n",
-    "# Find in a list with no matches\n",
-    "node = linked_list.find('aaa')\n",
-    "print(node)"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {
-    "collapsed": false
-   },
-   "outputs": [],
-   "source": [
-    "# Test delete\n",
-    "# Delete in an empty list\n",
-    "linked_list = LinkedList(None)\n",
-    "linked_list.delete('a')\n",
-    "linked_list.print_list()\n",
-    "# Delete a NULL\n",
-    "head = Node(10)\n",
-    "linked_list = LinkedList(head)\n",
-    "linked_list.delete(None)\n",
-    "linked_list.print_list()\n",
-    "# Delete in a list with one element or more matching elements\n",
-    "head = Node(10)\n",
-    "linked_list = LinkedList(head)\n",
-    "linked_list.insert_to_front('a')\n",
-    "linked_list.insert_to_front('bc')\n",
-    "linked_list.delete('a')\n",
-    "linked_list.print_list()\n",
-    "# Delete in a list with no matches\n",
-    "linked_list.delete('aa')"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {
-    "collapsed": false
-   },
-   "outputs": [],
-   "source": [
-    "# Test length\n",
-    "# Zero elements\n",
-    "linked_list = LinkedList(None)\n",
-    "print(len(linked_list))\n",
-    "# One or more elements\n",
-    "head = Node(10)\n",
-    "linked_list = LinkedList(head)\n",
-    "linked_list.insert_to_front('a')\n",
-    "linked_list.insert_to_front('bc')\n",
-    "print(len(linked_list))"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {
-    "collapsed": false
-   },
-   "outputs": [],
-   "source": [
-    "# Test empty print\n",
-    "linked_list = LinkedList(None)\n",
-    "linked_list.print_list()"
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "class Test(object):\n",
+    "    def test_insert_to_front(self):\n",
+    "        print('Test: insert_to_front on an empty list')\n",
+    "        linked_list = LinkedList(None)\n",
+    "        linked_list.insert_to_front(10)\n",
+    "        assert_equal(linked_list.get_all_data(), [10])\n",
+    "\n",
+    "        print('Test: insert_to_front on a NULL')\n",
+    "        linked_list.insert_to_front(None)\n",
+    "        assert_equal(linked_list.get_all_data(), [10])\n",
+    "\n",
+    "        print('Test: insert_to_front general case')\n",
+    "        linked_list.insert_to_front('a')\n",
+    "        linked_list.insert_to_front('bc')\n",
+    "        assert_equal(linked_list.get_all_data(), ['bc', 'a', 10])\n",
+    "        \n",
+    "        print('Success: test_insert_to_front\\n')\n",
+    "        \n",
+    "    def test_append(self):\n",
+    "        print('Test: append on an empty list')\n",
+    "        linked_list = LinkedList(None)\n",
+    "        linked_list.append(10)\n",
+    "        assert_equal(linked_list.get_all_data(), [10])\n",
+    "\n",
+    "        print('Test: append a NULL')\n",
+    "        linked_list.append(None)\n",
+    "        assert_equal(linked_list.get_all_data(), [10])\n",
+    "\n",
+    "        print('Test: append general case')\n",
+    "        linked_list.append('a')\n",
+    "        linked_list.append('bc')\n",
+    "        assert_equal(linked_list.get_all_data(), [10, 'a', 'bc'])\n",
+    "        \n",
+    "        print('Success: test_append\\n')\n",
+    "        \n",
+    "    def test_find(self):\n",
+    "        print('Test: find on an empty list')\n",
+    "        linked_list = LinkedList(None)\n",
+    "        node = linked_list.find('a')\n",
+    "        assert_equal(node, None)\n",
+    "\n",
+    "        print('Test: find a NULL')\n",
+    "        head = Node(10)\n",
+    "        linked_list = LinkedList(head)\n",
+    "        node = linked_list.find(None)\n",
+    "        assert_equal(node, None)\n",
+    "\n",
+    "        print('Test: find general case with matches')\n",
+    "        head = Node(10)\n",
+    "        linked_list = LinkedList(head)\n",
+    "        linked_list.insert_to_front('a')\n",
+    "        linked_list.insert_to_front('bc')\n",
+    "        node = linked_list.find('a')\n",
+    "        assert_equal(str(node), 'a')\n",
+    "\n",
+    "        print('Test: find general case with no matches')\n",
+    "        node = linked_list.find('aaa')\n",
+    "        assert_equal(node, None)\n",
+    "        \n",
+    "        print('Success: test_find\\n')\n",
+    "        \n",
+    "    def test_delete(self):\n",
+    "        print('Test: delete on an empty list')\n",
+    "        linked_list = LinkedList(None)\n",
+    "        linked_list.delete('a')\n",
+    "        assert_equal(linked_list.get_all_data(), [])\n",
+    "\n",
+    "        print('Test: delete a NULL')\n",
+    "        head = Node(10)\n",
+    "        linked_list = LinkedList(head)\n",
+    "        linked_list.delete(None)\n",
+    "        assert_equal(linked_list.get_all_data(), [10])\n",
+    "\n",
+    "        print('Test: delete general case with matches')\n",
+    "        head = Node(10)\n",
+    "        linked_list = LinkedList(head)\n",
+    "        linked_list.insert_to_front('a')\n",
+    "        linked_list.insert_to_front('bc')\n",
+    "        linked_list.delete('a')\n",
+    "        assert_equal(linked_list.get_all_data(), ['bc', 10])\n",
+    "\n",
+    "        print('Test: delete general case with no matches')\n",
+    "        linked_list.delete('aa')\n",
+    "        assert_equal(linked_list.get_all_data(), ['bc', 10])\n",
+    "        \n",
+    "        print('Success: test_delete\\n')\n",
+    "        \n",
+    "    def test_len(self):\n",
+    "        print('Test: len on an empty list')\n",
+    "        linked_list = LinkedList(None)\n",
+    "        assert_equal(len(linked_list), 0)\n",
+    "\n",
+    "        print('Test: len general case')\n",
+    "        head = Node(10)\n",
+    "        linked_list = LinkedList(head)\n",
+    "        linked_list.insert_to_front('a')\n",
+    "        linked_list.insert_to_front('bc')\n",
+    "        assert_equal(len(linked_list), 3)\n",
+    "        \n",
+    "        print('Success: test_len\\n')\n",
+    "\n",
+    "if __name__ == '__main__':\n",
+    "    test = Test()\n",
+    "    test.test_insert_to_front()\n",
+    "    test.test_append()\n",
+    "    test.test_find()\n",
+    "    test.test_delete()\n",
+    "    test.test_len()"
    ]
   }
  ],
diff --git a/linked-lists/linked_list.py b/linked-lists/linked_list.py
index e27e97b..f6406a8 100644
--- a/linked-lists/linked_list.py
+++ b/linked-lists/linked_list.py
@@ -28,6 +28,7 @@ class LinkedList(object):
         else:
             node.next = self.head
             self.head = node
+        return node
             
     def append(self, data, next_node=None):
         if data is None:
@@ -40,6 +41,7 @@ class LinkedList(object):
             while curr_node.next is not None:
                 curr_node = curr_node.next
             curr_node.next = node
+        return node
             
     def find(self, data):
         if data is None:
@@ -52,6 +54,7 @@ class LinkedList(object):
                 return curr_node
             else:
                 curr_node = curr_node.next
+        return
                 
     def delete(self, data):
         if data is None:
@@ -72,4 +75,12 @@ class LinkedList(object):
         curr_node = self.head
         while curr_node is not None:
             print(curr_node.data)
-            curr_node = curr_node.next
\ No newline at end of file
+            curr_node = curr_node.next
+
+    def get_all_data(self):
+        data = []
+        curr_node = self.head
+        while curr_node is not None:
+            data.append(curr_node.data)
+            curr_node = curr_node.next
+        return data
\ No newline at end of file