     "execution_count": 2,
     "metadata": {
      "collapsed": false
     },
     "outputs": [],
     "source": [
      "def height(node):\n",
      "    if node is None:\n",
      "        return 0\n",
      "    return 1 + max(height(node.left), \n",
 
</s> remove    "execution_count": 4,
 </s> add    "execution_count": 5, </s> remove    "execution_count": 3,
 </s> add    "execution_count": 4,
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Writing height.py\n"
     ]
    }
   ],
     "execution_count": 2,
     "metadata": {
      "collapsed": false
     },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Writing height.py\n"
     ]
    }
   ],
     "source": [
      "def height(node):\n",
      "    if node is None:\n",
      "        return 0\n",
      "    return 1 + max(height(node.left), \n",
keep keep keep keep replace keep keep keep keep keep
 Saved tree height challenge solution so it can be reused as a component to other related challenges. 
graphs_trees/tree_height/height_solution.ipynb