Regex.sym.src: def of bend-kit-regex@0.8.0.0
Import: import bend-kit-regex@0.8.0.0/regex.bend as Regex
Lines 1613-1621 of bend-kit-regex@0.8.0.0/regex.bend: https://jend.leeeet.dev/read.txt?path=bend-kit-regex@0.8.0.0/regex.bend&start_line=1613&end_line=1621

import Base

# The index in the last slot.
def sym.src(xs: List<&2, Maybe<&2, U32>>) -> U32:
  match xs:
    case Con{Some{x}, Nil{}}:
      x
    case Con{h, t}:
      sym.src(t)
    case Nil{}:
      seed.id()

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=Maybe
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=bend-kit-regex@0.8.0.0/regex.bend&name=seed.id