      "\n",
      "### In-Order Traversal (Provided)\n",
      "\n",
      "* 5, 2, 8, 1, 3 -> 1, 2, 3, 5, 8\n",
      "* 1, 2, 3, 4, 5 -> 1, 2, 3, 4, 5"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
 
</s>
    "* 1, 2, 3, 4, 5 -> 1, 2, 3, 4, 5\n",
    "\n",
    "If the `root` input is `None`, return a tree with the only element being the new root node."
      "\n",
      "### In-Order Traversal (Provided)\n",
      "\n",
      "* 5, 2, 8, 1, 3 -> 1, 2, 3, 5, 8\n",
    "* 1, 2, 3, 4, 5 -> 1, 2, 3, 4, 5\n",
    "\n",
    "If the `root` input is `None`, return a tree with the only element being the new root node."
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
keep keep keep keep replace keep keep keep keep keep
 Polish bst challenge and solution

Add root is None input test case.  Update time and space complexity discussion.
graphs_trees/bst/bst_solution.ipynb