def Int.read.add
import bend-kit-int@0.2.0.0/int.bend as Intimport Base
373def Int.read.add(+n: Nat, d: Word(n), o: Bool & Word(n)) -> Maybe<&2, Word(n)>:
374 (ov, m) = o
375 match ov:
376 case True{}:
377 None{}
378 case False{}:
379 Int.checked(n, Int.add_ov(n, False{}, m, d))