diff --git a/stacks_queues/queue_from_stacks/queue_from_stacks_challenge.ipynb b/stacks_queues/queue_from_stacks/queue_from_stacks_challenge.ipynb
index c1ebb7a..b633420 100644
--- a/stacks_queues/queue_from_stacks/queue_from_stacks_challenge.ipynb
+++ b/stacks_queues/queue_from_stacks/queue_from_stacks_challenge.ipynb
@@ -34,9 +34,13 @@
    "source": [
     "## Constraints\n",
     "\n",
-    "* Do you expect the methods to be enqueue and dequeue?\n",
+    "* Do we expect the methods to be enqueue and dequeue?\n",
     "    * Yes\n",
     "* Can we assume we already have a stack class that can be used for this problem?\n",
+    "    * Yes\n",
+    "* Can we push a None value to the Stack?\n",
+    "    * No\n",
+    "* Can we assume this fits memory?\n",
     "    * Yes"
    ]
   },
@@ -179,21 +183,21 @@
  ],
  "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/stacks_queues/queue_from_stacks/queue_from_stacks_solution.ipynb b/stacks_queues/queue_from_stacks/queue_from_stacks_solution.ipynb
index c6dbebf..4a0caed 100644
--- a/stacks_queues/queue_from_stacks/queue_from_stacks_solution.ipynb
+++ b/stacks_queues/queue_from_stacks/queue_from_stacks_solution.ipynb
@@ -33,9 +33,13 @@
    "source": [
     "## Constraints\n",
     "\n",
-    "* Do you expect the methods to be enqueue and dequeue?\n",
+    "* Do we expect the methods to be enqueue and dequeue?\n",
     "    * Yes\n",
     "* Can we assume we already have a stack class that can be used for this problem?\n",
+    "    * Yes\n",
+    "* Can we push a None value to the Stack?\n",
+    "    * No\n",
+    "* Can we assume this fits memory?\n",
     "    * Yes"
    ]
   },
@@ -65,7 +69,7 @@
     "\n",
     "### Enqueue\n",
     "\n",
-    "* If the left stack is empty and the right stack is not empty\n",
+    "* If right stack is not empty\n",
     "    * Shift the elements of the right stack to the left stack\n",
     "* Push the data to the left stack\n",
     "\n",
@@ -75,7 +79,7 @@
     "\n",
     "### Dequeue\n",
     "\n",
-    "* If the right stack is empty and the the left stack is not empty\n",
+    "* If the left stack is not empty\n",
     "    * Shift the elements of the left stack to the right stack\n",
     "* Pop from the right stack and return the data\n",
     "\n",
@@ -130,13 +134,11 @@
     "            destination.push(source.pop())\n",
     "\n",
     "    def enqueue(self, data):\n",
-    "        if self.left_stack.is_empty() and not self.right_stack.is_empty():\n",
-    "            self.shift_stacks(self.right_stack, self.left_stack)\n",
+    "        self.shift_stacks(self.right_stack, self.left_stack)\n",
     "        self.left_stack.push(data)\n",
     "\n",
     "    def dequeue(self):\n",
-    "        if self.right_stack.is_empty() and not self.left_stack.is_empty():\n",
-    "            self.shift_stacks(self.left_stack, self.right_stack)\n",
+    "        self.shift_stacks(self.left_stack, self.right_stack)\n",
     "        return self.right_stack.pop()"
    ]
   },
@@ -236,21 +238,21 @@
  ],
  "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,