anchor.diff:      "--offline"
       "--frozen-lockfile"
       "--ignore-engines"
  -    "--ignore-scripts"
     ];
   
     mkYarnModules = {
  
positive.code:     # we import package.json from the unfiltered source
      packageJSON = ./package.json;
  
      yarnFlags = defaultYarnFlags ++ ["--production=true"];
  
      nativeBuildInputs = [ pkgs.makeWrapper ];
  
  
negative.code:     yarnNix ? mkYarnNix { inherit yarnLock; },
      offlineCache ? importOfflineCache yarnNix,
      yarnFlags ? [ ],
      ignoreScripts ? true,
      pkgConfig ? {},
      preBuild ? "",
      postBuild ? "",
  