For me, it's being able to have a consistent code-style that is completely unambiguous for all collaborators. You configure the tools to run in your editor (or as make targets, or as pre-commit scripts) and you run the same checkers on your CI which prevents non-conforming changes from being merged to master.

Here's a config file for running some of these checks with https://pre-commit.com/ both locally, and then again on CI:

https://github.com/kogan/django-subscriptions/blob/master/.p...

https://github.com/kogan/django-subscriptions/blob/master/.c...