> And not just that they exist, but that they are specified per module Nitpick: editions are specified per crate, not per module. --- Also note that editions

> And not just that they exist, but that they are specified per module Nitpick: editions are specified per crate, not per module. --- Also note that editions allow to make mostly syntactic changes (add/remove syntax or change the meaning of existing ones), however it is greatly limited in what can be changed in the standard library because ultimately that is a crate dependency shared by all other crates.