REGION_ID is a code that Google assigns based on
the region you select when you create your app. Including
REGION_ID.r in App Engine URLs is optional for
existing apps and will soon be required for all new apps.
To ensure a smooth transition, we are slowly updating App Engine to use region IDs. If we haven't updated your Google Cloud project yet, you won't see a region ID for your app. Since the ID is optional for existing apps, you don't need to update URLs or make other changes once the region ID is available for your existing apps.
Learn more about region IDs.
This is the quickstart for Python 2. To get started with a Python app in App Engine, we recommend the Quickstart for Python 3.
As of January 1, 2020, the Python community no longer updates, fixes bugs, or patches security issues for Python 2.7. For more information, see Python 2 support on Google Cloud.