An alternative way to "forget" a value is to hand it off to another thread that then loops infinitely.

Could of course be plugged by saying `!Forget : !Send`, but wouldn't that preclude legitimate useful scenarios for `!Forget`?

> An alternative way to "forget" a value is to hand it off to another thread that then loops infinitely.

Might be able to address that by only allowing such a handoff to a thread spawned via some scoped abstraction to ensure that progress can only be made if/when the spawned thread terminates?