      "            temp = self.pop()\n",
      "            if buff.is_empty() or temp >= buff.peek():\n",
      "                buff.push(temp)\n",
      "            else:\n",
      "                while not buff.is_empty() and buff.peek() > temp:\n",
      "                    self.push(buff.pop())\n",
      "                buff.push(temp)\n",
      "        return buff"
     ]
    },
 
</s> remove     "            while not buff.is_empty() and buff.peek() > temp:\n",
 </s> add     "            while not buff.is_empty() and temp < buff.peek():\n", </s> remove     "%run ../stack/stack.py\n",
    "%load ../stack/stack.py"
 </s> add     "%run ../stack/stack.py" </s> remove    "version": "3.4.3"
 </s> add    "version": "3.5.0"
    "                while not buff.is_empty() and temp < buff.peek():\n",
      "            temp = self.pop()\n",
      "            if buff.is_empty() or temp >= buff.peek():\n",
      "                buff.push(temp)\n",
      "            else:\n",
    "                while not buff.is_empty() and temp < buff.peek():\n",
      "                    self.push(buff.pop())\n",
      "                buff.push(temp)\n",
      "        return buff"
     ]
    },
keep keep keep keep replace keep keep keep keep keep
 Update stack min challenge (#108)

Updates constraints and solution. 
stacks_queues/sort_stack/sort_stack_solution.ipynb