def co.at
import ezx@1.11.0.0/src/add/plan.bend as Planimport Base
import ezx@1.11.0.0/src/add/world.bend as A
import ezx@1.11.0.0/src/lock/up.bend as Up
248# the checkout at a rev, as the World answered it
249def co.at(+world: A.World, +rev: String) -> Co:
250 co.heard(Up.heard(A.replies(world), ask.of(QClone{rev}, A.from(world))))