anchor.diff: -{ attrs
  +{ lib
  +, attrs
   , buildPythonPackage
   , defusedxml
   , fetchPypi
  
positive.code: 
    nativeBuildInputs = [
      setuptools-scm-git-archive
      setuptools_scm
    ];
  
    checkInputs = [
      attrs
      hypothesis
      pillow
      pytestCheckHook
      pytest-helpers-namespace
      pytest-timeout
      pytest_xdist
      pytestrunner
      python-dateutil
      python-xmp-toolkit
    ];
  
    propagatedBuildInputs = [ defusedxml lxml ];
  
    postPatch = ''
      sed -i \
        -e 's/^pytest .*/pytest/g' \
        -e 's/^attrs .*/attrs/g' \
        -e 's/^hypothesis .*/hypothesis/g' \
        requirements/test.txt
    '';
  
    preBuild = ''
      HOME=$TMPDIR
    '';
  
    meta = with lib; {
      homepage = "https://github.com/pikepdf/pikepdf";
  
negative.code: , isPy3k
  , lxml
  , pillow
  , psutil
  , pybind11
  , pytest-cov
  , pytest-helpers-namespace
  , pytest-timeout
  , pytest-xdist
  , pytestCheckHook
  , python-dateutil
  , python-xmp-toolkit
  , qpdf
  , setuptools-scm
  , setuptools-scm-git-archive
  }:
  
  buildPythonPackage rec {
    pname = "pikepdf";
    version = "2.5.2";
    disabled = ! isPy3k;
  
    src = fetchPypi {
      inherit pname version;
      sha256 = "sha256-j8PpeyTa+9SxrAV8jxRMGEZ85V00KhqMQmiIkOrVjvM=";
    };
  
    buildInputs = [
  