def through
import gralha-text-scan@0.1.0.1/scan.bend as Scanimport Base
97def through(+s: String, +p: String) -> String:
98 match s:
99 case SNil{}: ""
100 case SCon{sc, st}:
101 branch(String, prefix(s, p), _ => drop(s, p), _ => through(st, p))