PROOF.head: def of bend-kit-collections@0.1.4.1
Import: import bend-kit-collections@0.1.4.1/PROOF.bend as PROOF
Lines 133-138 of bend-kit-collections@0.1.4.1/PROOF.bend: https://jend.leeeet.dev/read.txt?path=bend-kit-collections@0.1.4.1/PROOF.bend&start_line=133&end_line=138

import Base

def head(-K: Data, xs: List<&2, K>) -> Maybe<&2, K>:
  match xs:
    case Nil{}:
      None{}
    case Con{h, t}:
      Some{h}

Uses (2):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe