anchor.diff:  
     postPatch = ''
       substituteInPlace setup.py \
  -      --replace "docutils ~= 0.17.0" "docutils"
  +      --replace "docutils ~= 0.17.0" "docutils" \
  +      --replace "attrs>=19.1.0,<22" "attrs>=19.1.0"
     '';
  +
  +  nativeBuildInputs = [
  +    setuptools
  +  ];
   
     propagatedBuildInputs = [
       attrs
  
positive.code: { lib
  , buildPythonPackage
  , fetchPypi
  
  # propagtes
  , sigtools
  
negative.code: buildPythonPackage rec {
    pname = "clize";
    version = "4.2.1";
    format = "pyproject";
  
    src = fetchPypi {
      inherit pname version;
  