add external script into example_notebook (#731)

diagnostics/example_notebook/example_notebook.ipynb

@@ -314,13 +314,28 @@
    "outputs": [],
    "execution_count": null,
    "source": [
-    "# Part 4: Close the catalog files and\n",
+    "# Part 4: running an external script\n",
+    "# the use of external python scripts can help prevent bloat in the notebook\n",
+    "# here, we show how this can be done\n",
+    "sys.path.append(os.environ[\"POD_HOME\"])\n",
+    "import script\n",
+    "script.HelloWorld()"
+   ],
+   "id": "dfff0ee7ac28d733"
+  },
+  {
+   "metadata": {},
+   "cell_type": "code",
+   "outputs": [],
+   "execution_count": null,
+   "source": [
+    "# Part 5: Close the catalog files and\n",
     "# release variable dict reference for garbage collection\n",
     "# ------------------------------------------------------\n",
     "cat.close()\n",
     "tas_dict = None\n",
     "\n",
-    "# Part 5: Confirm POD executed successfully\n",
+    "# Part 6: Confirm POD executed successfully\n",
     "# ----------------------------------------\n",
     "print(\"Last log message by example_multicase POD: finished successfully!\")"
    ],

diagnostics/example_notebook/script.py

@@ -0,0 +1,4 @@
+# script to showcase launching external scripts in the notebook
+
+def HelloWorld():
+    print("Hello, world!")