def Deque.pop_back.halves
import bend-kit-collections@0.1.4.1/deque.bend as Dequeimport Base
120def Deque.pop_back.halves(
121 a, -A: Kind(a), sm: List<a, A> & List<a, A>
122) -> Maybe<&1, A & Deque<a, A>>:
123 (stay, move) = sm
124 Deque.pop_back.go(a, A, List.reverse(a, A, move), stay)