Is PEP-8 a Code or More of a Guideline?

[Paul Rubin]

Steven D'Aprano <steve at REMOVE.THIS.cybersource.com.au> writes:
> There was also Hypercard from Apple in (by memory) 1988. Although case was
> not significant, handlers were usually written mouseDown, mouseUp,
> openStack, openCard, etc.

Apple (*cough*) Xerox PARC (*cough*).  I think that style got into the
Macintosh by way of Smalltalk, and got into X11 the same way
indirectly, via the CMU Andrew system and its relatives that also were
influenced by Smalltalk.