Does Python really follow its philosophy of "Readability counts"?

[Terry Reedy]

Steven D'Aprano wrote:
>
> Here's a thought experiment for you. You've suggested that the values 
> returned by cmp() are allowed to change "at whim". Okay, let's do it: 
> make a patch that changes cmp() to return -17, 0 or 53, and promise to 
> support it for at least three years. Try to get it accepted on python-
> dev. What do you expect they will say?
> 
> My money is on them saying "No, this will pointlessly break code for no 
> good reason. Rejected."

I have occasionally thought that things documented to possibly change 
*should* be changed just to expose the *bug* of depending on them not 
changing.  Or maybe, the doc should be changed.