anchor.diff:    , libGLU
     , libX11
     , six
  +  , pytest
  +  , makeFontsConf
  +  , freefont_ttf
   }:
   
  -let 
  +let
     pythonocc-core-cadquery = stdenv.mkDerivation {
       pname = "pythonocc-core-cadquery";
       version = "0.18.2";
  
positive.code:   , buildPythonPackage
    , isPy3k
    , pythonOlder
    , fetchFromGitHub
    , pyparsing
    , opencascade
  
negative.code: in
    buildPythonPackage rec {
      pname = "cadquery";
      version = "2.0";
  
      src = fetchFromGitHub {
        owner = "CadQuery";
        repo = pname;
        rev = version;
        sha256 = "1n63b6cjjrdwdfmwq0zx1xabjnhndk9mgfkm4w7z9ardcfpvg84l";
      };
  
      buildInputs = [
        opencascade
      ];
  
      propagatedBuildInputs = [
        pyparsing
        pythonocc-core-cadquery
      ];
  
      FONTCONFIG_FILE = makeFontsConf {
        fontDirectories = [ freefont_ttf ];
      };
  
      checkInputs = [
        pytest
      ];
  
      disabled = pythonOlder "3.6" || pythonAtLeast "3.8";
  
      meta = with lib; {
        description = "Parametric scripting language for creating and traversing CAD models";
        homepage = "https://github.com/CadQuery/cadquery";
  