anchor.diff:    propagatedBuildInputs = [ defusedxml lxml ];
   
     postPatch = ''
  -    substituteInPlace requirements/test.txt \
  -       --replace "pytest >= 3.6.0, < 4.1.0" "pytest >= 4.2.1, < 5"
  +    sed -i \
  +      -e 's/^pytest .*/pytest/g' \
  +      -e 's/^attrs .*/attrs/g' \
  +      -e 's/^hypothesis .*/hypothesis/g' \
  +      requirements/test.txt
     '';
   
     preBuild = ''
  
positive.code:     maintainers = [ maintainers.kiwi ];
    };
  }
  
  
negative.code: 
  buildPythonPackage rec {
    pname = "pikepdf";
    version = "1.6.2";
    disabled = ! isPy3k;
  
    src = fetchPypi {
      inherit pname version;
      sha256 = "1x1b55znr0j4fib69l2h0xq0qmbf2nbxwbwd4f7y8r4sqi20239z";
    };
  
    buildInputs = [
  