> 2004 puts us at Python 2.4 or so, but I think that's just when it got formalized into a PEP

I didn't notice the date on the PEP, but I think you're right. I remember reading it when I learned Python circa 2002.

Found this (from 1999): https://mail.python.org/pipermail/python-list/1999-June/0019....