anchor.diff:      };
     };
   in
  -  pyparsing
  +pyparsing
  
positive.code: { buildPythonPackage
  , fetchFromGitHub
  , lib
  
  # since this is a dependency of pytest, we need to avoid
  # circular dependencies
  , jinja2
  , pytestCheckHook
  , railroad-diagrams
  
negative.code: let
    pyparsing = buildPythonPackage rec {
      pname = "pyparsing";
      version = "3.0.9";
      format = "pyproject";
  
      src = fetchFromGitHub {
        owner = "pyparsing";
        repo = pname;
        rev = "pyparsing_${version}";
        sha256 = "sha256-aCRyJQyLf8qQ6NO41q+HC856TjIHzIt0vyVBLV+3teE=";
      };
  
      nativeBuildInputs = [
        flit-core
      ];
  
      # circular dependencies with pytest if enabled by default
      doCheck = false;
      checkInputs = [
        jinja2
  