      "To prevent multiple dequeue calls from needlessly shifting elements around between the stacks, we'll shift elements in a lazy manner.\n",
      "\n",
      "### Enqueue\n",
      "\n",
      "* If the left stack is empty and the 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",
      "Complexity:\n",
      "* Time: O(n)\n",
 
</s> remove     "* If the right stack is empty and the the left stack is not empty\n",
 </s> add     "* If the left stack is not empty\n", </s> remove     "* Do you expect the methods to be enqueue and dequeue?\n",
 </s> add     "* Do we expect the methods to be enqueue and dequeue?\n", </s> remove     "* Do you expect the methods to be enqueue and dequeue?\n",
 </s> add     "* Do we expect the methods to be enqueue and dequeue?\n",
    "* If right stack is not empty\n",
      "To prevent multiple dequeue calls from needlessly shifting elements around between the stacks, we'll shift elements in a lazy manner.\n",
      "\n",
      "### Enqueue\n",
      "\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",
      "Complexity:\n",
      "* Time: O(n)\n",
keep keep keep keep replace keep keep keep keep keep
 Polish queue from stacks challenge and solution (#74)

Update constraints, algorithm discussion, and code. 
stacks_queues/queue_from_stacks/queue_from_stacks_solution.ipynb