anchor.diff:    postPatch = ''
       substituteInPlace setup.py \
         --replace "lxml<=4.3.5" "lxml~=4.3" \
  +      --replace "isbnlib>=3.9.1,<3.10" "isbnlib~=3.9" \
         --replace "python-slugify>=1.2.6,<4" "python-slugify"
     '';
   
  
positive.code:   doCheck = !stdenv.isDarwin && pythonOlder "3.8";
  
    checkInputs = ([
      pytest
    ]) ++ [
      xdg_utils
    ];
  
negative.code: 
  buildPythonPackage rec {
    pname = "papis";
    version = "0.10";
    disabled = !isPy3k;
  
    # Missing tests on Pypi
  