      "* If we call this function on an empty stack, can we return sys.maxsize?\n",
      "    * Yes\n",
      "* Can we assume we already have a stack class that can be used for this problem?\n",
      "    * Yes"
     ]
    },
    {
 
</s> remove     "* If we call this function on an empty stack, can we return maxsize?\n",
 </s> add     "* Can we assume the input values for push are valid?\n",
    "    * Yes\n",
    "* If we call this function on an empty stack, can we return sys.maxsize?\n", </s> remove     "* Space: O(n)\n",
 </s> add     "* Space: O(1)\n", </s> remove     "        stack = MyStack()\n",
 </s> add     "        stack = StackMin()\n",
    "    * Yes\n",
    "* Can we assume this fits memory?\n",
      "* If we call this function on an empty stack, can we return sys.maxsize?\n",
      "    * Yes\n",
      "* Can we assume we already have a stack class that can be used for this problem?\n",
    "    * Yes\n",
    "* Can we assume this fits memory?\n",
      "    * Yes"
     ]
    },
    {
keep keep add keep keep keep keep
 Polish stack min challenge and solution (#72)

Update constraints, algorithm discussion, code, and tests. 
stacks_queues/stack_min/stack_min_solution.ipynb