Your own .py file can also be a module. This lesson keeps one editable main.py tab: its supplied setup writes route_rules.py into the browser's temporary in-memory filesystem, then imports its travel_minutes function. The file is not saved to your computer and will not survive a fresh session. On your machine you would keep route_rules.py beside main.py; the current lesson runner submits one active Python file, so the setup creates that local module before importing it. Change the call from 2 to 3 stops; Run and compare the result.
travel_minutes call to 3 so it prints 15.Edit main.py, press Run to inspect the result, then Submit to check your change.
Change only the argument to the final imported-function call.