Someone correct me if I'm wrong, but, I think it was less of "tacking on closures" and more of getting the lexical scoping issues right. i.e, there was issues

Someone correct me if I'm wrong, but, I think it was less of "tacking on closures" and more of getting the lexical scoping issues right. i.e, there was issues with scoping that had nothing to do with closures per-se. When they fixed it, closures automatically became possible.