anchor.diff:      gpio = mkSubProject {
         subprj = "gpio";
         buildInputs = [
  +        libxcrypt
           passthru.wiringPi
           passthru.devLib
         ];
  
positive.code:     wiringPiD = mkSubProject {
        subprj = "wiringPiD";
        buildInputs = [
          passthru.wiringPi
          passthru.devLib
        ];
  
negative.code: , stdenv
  , symlinkJoin
  , fetchFromGitHub
  , libxcrypt
  }:
  
  let
  