      "        if self.last_stack.num_items == 0:\n",
      "            self.stacks.pop()\n",
      "            self.last_stack = self.stacks[len(self.stacks)-1] \\\n",
      "                if len(self.stacks) else None\n",
      "            num_stacks = len(self.stacks)\n",
      "        return data"
     ]
    },
    {
     "cell_type": "markdown",
 
</s> remove     "            self.last_stack = StackWithCapacity(None, self.capacity)\n",
 </s> add     "            self.last_stack = StackWithCapacity(None, self.indiv_stack_capacity)\n", </s> remove     "    def __init__(self, capacity):\n",
    "        self.capacity = capacity\n",
 </s> add     "    def __init__(self, indiv_stack_capacity):\n",
    "        self.indiv_stack_capacity = indiv_stack_capacity\n", </s> remove     "        stacks = SetOfStacks(capacity=2)\n",
 </s> add     "        stacks = SetOfStacks(indiv_stack_capacity=2)\n",
      "        if self.last_stack.num_items == 0:\n",
      "            self.stacks.pop()\n",
      "            self.last_stack = self.stacks[len(self.stacks)-1] \\\n",
      "                if len(self.stacks) else None\n",

      "        return data"
     ]
    },
    {
     "cell_type": "markdown",
keep keep keep keep replace keep keep keep keep keep
 Polish set of stacks challenge and solution (#73)

Update constraints, algorithm discussion, and code. 
stacks_queues/set_of_stacks/set_of_stacks_solution.ipynb