def step_acc
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
149def step_acc(~T: Data, op: E.Op<T>, st: Deque<T> & List<&2, E.Obs<T>>) -> Deque<T> & List<&2, E.Obs<T>>:
150 (d, acc) = st
151 record(~T, acc, step(~T, d, op))