      "\n",
      "* If the list is empty, return NULL\n",
      "* If the list has one node\n",
      "    * Save the first node's value\n",
      "    * Set first and last to NULL\n",
      "    * Return the saved value\n",
      "* Else\n",
      "    * Save the first node's value\n",
      "    * Set first to its next node\n",
      "    * Return the saved value\n",
 
</s> remove     "* If the list is empty, return NULL\n",
 </s> add     "* If the list is empty, return None\n", </s> remove     "        node = Node(data)\n",
    "        if self.first is None and self.last is None:\n",
    "            self.first = node\n",
    "            self.last = node\n",
    "        else:\n",
    "            self.last.next = node\n",
    "            self.last = node\n",
 </s> add     "        # TODO: Implement me\n",
    "        pass\n", </s> remove     "        # Empty list\n",
    "        if self.first is None and self.last is None:\n",
    "            return None\n",
    "        \n",
    "        # Remove only element from a one element list\n",
    "        elif self.first == self.last:\n",
    "            data = self.first.data\n",
    "            self.first = None\n",
    "            self.last = None\n",
    "            return data\n",
    "        else:\n",
    "            data = self.first.data\n",
    "            self.first = self.first.next\n",
    "            return data"
 </s> add     "        # TODO: Implement me\n",
    "        pass" </s> remove     "        self.first = None\n",
    "        self.last = None\n",
 </s> add     "        # TODO: Implement me\n",
    "        pass\n", </s> remove     "        self.data = data\n",
    "        self.next = None\n",
 </s> add     "        # TODO: Implement me\n",
    "        pass\n",
    "    * Set first and last to None\n",
      "\n",
      "* If the list is empty, return NULL\n",
      "* If the list has one node\n",
      "    * Save the first node's value\n",
    "    * Set first and last to None\n",
      "    * Return the saved value\n",
      "* Else\n",
      "    * Save the first node's value\n",
      "    * Set first to its next node\n",
      "    * Return the saved value\n",
keep keep keep keep replace keep keep keep keep keep
 Cleared queue challenge code section.  Changed references from NULL to None to be more Pythonic. 
stacks_queues/queue_list/queue_list_solution.ipynb