OK, it's 100% likely I saw it, just so rarely I can't remember.
Testing. Over that long time I have used many test frameworks. My normal workflow is to try and exercise all the code I write as I go.
On the other hand I am 100% pedantic about using 'schema' (https://pypi.org/project/schema/) to validate all the types, structure and domains when I read json.
Nearly the same here.
The only type error I make a little bit more than I would like, is expecting an iterable and passing a string instead, because I forgot parentheses around arguments.
But I made way more type errors when programming in C/++.
'schema' is more a schema enhanced by python than just a checker. It can convert types, set defaults so after 'Box' I can simple access config with a.b.c.
It may be subtle but it is much more powerful than it looks.
There are many of these things. Maybe some are better but I like this one.
