def obs_nat
import bend-collections@1.0.0.0/src/containers/bitset.bend as Bitsetimport Base
import bend-collections@1.0.0.0/src/containers/types/bitset.bend as E
504def obs_nat(r: Bitset & Nat) -> Bitset & E.Obs:
505 (s, x) = r
506 (s, E.ONat{x})