anchor.diff:  
     nativeBuildInputs = [ makeWrapper ];
   
  -  propagatedBuildInputs = with pythonPackages; [ requests vobject lxml ];
  +  propagatedBuildInputs = with python3Packages; [ requests vobject lxml ];
  +
  +  strictDeps = true;
   
     doCheck = false; # no test
   
  
positive.code: { lib, stdenv, fetchgit, python, pythonPackages, makeWrapper }:
  
  stdenv.mkDerivation {
  
  
negative.code:     mkdir -p $out/bin
      cp $src/carddav-util.py $out/bin
  
      pythondir="$out/lib/${python3Packages.python.sitePackages}"
      mkdir -p "$pythondir"
      cp $src/carddav.py "$pythondir"
    '';
  