> For the longest time it had static assert(Rs.length == 2);, including in the latest release.

Good point.

> Doing set intersection for RoRs... is surely just RoRs.chain().setIntersection() if we use the unary case for an RoR implementation.

True.

I'll add the restriction, but I'm still *personally* on the fence about providing and `RoR` *overload*. Don't know if I outright *object* to it or anything, but I won't take the initiative of writing it either.