def next.cut
import bend-kit-journal@0.3.1.0/journal.bend as Journalimport Base
48def next.cut(~P: Type, ~S: Type, ~skip: S -> @+hs:U32 -> @+len:U32 -> S, ~sum: P -> P & U32, +want: U32, +len: U32, r: S & P) -> Step<P, S>:
49 (s, p) = r
50 next.summed(~P, ~S, ~skip, want, len, s, sum(p))