Update exercise05.ipynb

Author: fs446

exercise05.ipynb

@@ -139,7 +139,7 @@
     "        shutil.rmtree(path_gen)\n",
     "    except OSError as e:\n",
     "        print(\"Error: %s : %s\" % (path_gen, e.strerror))\n",
-    "    os.mkdir(path_gen)\n",
+    "    os.makedirs(path_gen)\n",
     "    path_multi = \"multi_track\"\n",
     "    os.mkdir(path_gen + path_multi)\n",
     "\n",