Sigv4.pairs: def of bend-kit-sigv4@0.11.0.1
Import: import bend-kit-sigv4@0.11.0.1/sigv4.bend as Sigv4
Lines 151-156 of bend-kit-sigv4@0.11.0.1/sigv4.bend: https://jend.leeeet.dev/read.txt?path=bend-kit-sigv4@0.11.0.1/sigv4.bend&start_line=151&end_line=156

import Base

def pairs(xs: List<&2, String>) -> List<&2, Sigma<&2, &2, String, _ => String>>:
  match xs:
    case Nil{}:
      Nil{}
    case Con{+h, t}:
      pairs.if(String.is_empty(h), h, pairs(t))

Uses (5):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Sigma
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String.is_empty
  https://jend.leeeet.dev/definition.txt?path=bend-kit-sigv4@0.11.0.1/sigv4.bend&name=pairs.if