A> Hrm. But until it's no longer a separate package, why use A> 2.2-specific features in the builtin package?
Because it's convenient, and the semantics are subtly different (and IMO suboptimal) without them. E.g. the builtin version uses a generator in a few places, while the standalone version uses an iterator. The generator version is much more intuitive, but to write cross-version code that uses that interface you need to do something like call list() on a return value.