minor fix to keras optimization notebook

Author: lukmanr

00_Miscellaneous/model_optimisation/Tutorial - TensorFlow Model Optimisation for Serving - MNIST with Keras.ipynb

@@ -396,7 +396,9 @@
     "if tf.gfile.Exists(model_dir):\n",
     "    print(\"Removing previous artifacts...\")\n",
     "    tf.gfile.DeleteRecursively(model_dir)\n",
-    "    \n",
+    "\n",
+    "os.makedirs(model_dir)\n",
+    "\n",
     "estimator = run_experiment(params, run_config)"
    ]
   },
@@ -586,7 +588,8 @@
     }
    ],
    "source": [
-    "saved_model_dir = os.path.join(export_dir, os.listdir(export_dir)[-1]) \n",
+    "saved_model_dir = os.path.join(\n",
+    "    export_dir, [f for f in os.listdir(export_dir) if f.isdigit()][0])\n",
     "print(saved_model_dir)\n",
     "inference_test(saved_model_dir)"
    ]