def digits
import yaml-for-bend@0.1.1.0/scan.bend as Scanimport Base
1245def digits(s: String) -> Taken:
1246 match s:
1247 case SNil{}:
1248 Taken{"", 0n}
1249 case SCon{+c, t}:
1250 took.or(Bool.not(Char.is_digit(c)), u => taken.cons(c, 1n, digits(t)))