typo_fix:definying->defining, problemn->problem

Author: parkjin-nim

examples/advanced-tour.ipynb

@@ -520,7 +520,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.7"
+   "version": "3.5.2"
   }
  },
  "nbformat": 4,