Retro, you are blowing this way out of proportion.  Style guidelines are
not absolute rules that must be followed at all cost, and there are
always exceptions.  You need to have a lot of experience before you can
claim with certainty that a certain piece of code should or should not
be formatted according to the style guidelines.  (This is as opposed to
the syntax of the language, which is an absolute set of rules where
violations raise a SyntaxError.)

In this case, the PEP never meant to say that all arithmetic operators
have to be surrounded by spaces.  That would make just as little sense
as requiring no spaces.  The words in the PEP cannot possibly
approximate the set of heuristics I have in my mind for this purpose, 
and I don't think they have to.  When I wrote PEP 8 (or actually its
precursor), I was merely *suggesting* that certain uses of spaces look
better than others.  If you are interpreting this as requiring all
examples needing to follow the literal style guide, well, Im sorry, but
that's not how it was meant, and I am not willing to either change the
examples (the specific one you quote looks just fine to me) or to edit
the PEP to try and formulate a more complex rule.  In my experience, the
more baroque the rule the more arguments it elicits.