In my humble opinion, this doesn't warrant the creation of a new structure, but
rather a restructuring of PEPs.
As mentioned by others, we have a "Rejected Ideas" section already, but that
seems to somewhat miss the point. It captures only the arguments that have won,
arguments moved against
What about `case for Point(x, 0):`? It reads very naturally, the presence of
"for" hints against Point() being a call to the class, and "for" is an existing
keyword that would make no other sense in that position.
Examples with other formats such as `case for [x, 0]:` seem to work just as
well.
