This example uses the @ytt/data
library to declare configuration data in yml.
The yml data is then processed in a pythonic script (starlark is a limited variant of python).
To see this example live, vist: https://get-ytt.io/#gist:https://gist.github.com/JollyWizard/7a735c3477fe7a5ec20d926088f59fd3