Point.set_top: def of bend-collections@1.0.0.0
Import: import bend-collections@1.0.0.0/src/crypto/ed25519/point.bend as Point
Lines 113-123 of bend-collections@1.0.0.0/src/crypto/ed25519/point.bend: https://jend.leeeet.dev/read.txt?path=bend-collections@1.0.0.0/src/crypto/ed25519/point.bend&start_line=113&end_line=123

import Base

# the last byte with bit 7 set to b (the canonical y has it clear)
def set_top(xs: List<&2, U32>, +b: U32) -> List<&2, U32>:
  match xs:
    case Nil{}:
      Nil{}
    case Con{x, xt}:
      match xt:
        case Nil{}:
          Con{U32.or(x, U32.shln(b, 7n)), Nil{}}
        case Con{y, yt}:
          Con{x, set_top(Con{y, yt}, b)}

Uses (4):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.or
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.shln