      "* Visit the current node\n",
      "\n",
      "Complexity:\n",
      "* Time: O(n)\n",
      "* Space: O(log n)\n",
      "\n",
      "Note:\n",
      "* This is a form of a depth-first traversal"
     ]
    },
 
</s> remove     "* Space: O(log n)\n",
 </s> add     "* Space: O(h), where h is the height of the tree\n", </s> remove     "* Space: O(log n)\n",
 </s> add     "* Space: O(h), where h is the height of the tree\n",
    "* Space: O(h), where h is the height of the tree\n",
      "* Visit the current node\n",
      "\n",
      "Complexity:\n",
      "* Time: O(n)\n",
    "* Space: O(h), where h is the height of the tree\n",
      "\n",
      "Note:\n",
      "* This is a form of a depth-first traversal"
     ]
    },
keep keep keep keep replace keep keep keep keep keep
 Fixed Big O space complexities. 
graphs_trees/tree_dfs/dfs_solution.ipynb