Hdr.len.ok: def of bend-toon-codec@0.1.0.0
Import: import bend-toon-codec@0.1.0.0/src/hdr.bend as Hdr
Lines 147-149 of bend-toon-codec@0.1.0.0/src/hdr.bend: https://jend.leeeet.dev/read.txt?path=bend-toon-codec@0.1.0.0/src/hdr.bend&start_line=147&end_line=149

import Base
import bend-toon-codec@0.1.0.0/src/head.bend as Hd

# A length is `0` or digits without a leading zero, at most nine of them.
def len.ok(+ds: String) -> Bool:
  len.ok.pick(String.is_empty(ds), String.eq(ds, "0"), Hd.lead(ds, 48), ds)

Uses (6):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String.eq
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String.is_empty
  https://jend.leeeet.dev/definition.txt?path=bend-toon-codec@0.1.0.0/src/hdr.bend&name=len.ok.pick
  https://jend.leeeet.dev/definition.txt?path=bend-toon-codec@0.1.0.0/src/head.bend&name=lead