It actually wasn’t fine to rename flatten() to flat() - flat isn’t a verb, flatten() seems natural, and now you have to explain to everyone that yes it’s called

It actually wasn’t fine to rename flatten() to flat() - flat isn’t a verb, flatten() seems natural, and now you have to explain to everyone that yes it’s called flat() because someone on a standards committee really likes unmaintained web sites that probably have expired domains, expired certs, non paid for hosting but might run mootools.