[jimbaker]

Walking the call stack implies using dynamic scope, which has hard edges, vs lexical scope. See my answer earlier in this thread https://news.ycombinator.com/item?id=41272285

It's been nearly 23 years, but Python 2.2 fixed this issue (https://docs.python.org/3/whatsnew/2.2.html#pep-227-nested-s...), and it's also why JavaScript added let (and const). f-string support also uses lexical scope, and it's an important part of its success.