def obs_nat
import bend-collections-laws-math@1.0.0.0/src/containers/deque.bend as Dequeimport Base
import bend-collections-laws-math@1.0.0.0/src/containers/types/deque.bend as E
114def obs_nat(~T: Data, r: Deque<T> & Nat) -> Deque<T> & E.Obs<T>:
115 (d, n) = r
116 (d, E.ONat{n})