anchor.diff:  , pythonOlder
   , attrs
   , bitstruct
  +, click
   , future
   , pathlib2
   , typing
  
positive.code:     pyyaml
    ] ++ lib.optional (pythonOlder "3.5") typing;
  
    checkInputs = [
      pytest
    ];
  
    checkPhase = ''
      pytest -s src/canmatrix
    '';
  
    meta = with lib; {
  
negative.code: 
  buildPythonPackage rec {
    pname = "canmatrix";
    version = "0.9.1";
  
    # uses fetchFromGitHub as PyPi release misses test/ dir
    src = fetchFromGitHub {
      owner = "ebroecker";
      repo = pname;
      rev = version;
      sha256 = "129lcchq45h8wqjvvn0rwpbmih4m0igass2cx7a21z94li97hcia";
    };
  
    propagatedBuildInputs = [
      # required
      attrs
      bitstruct
      click
      future
      pathlib2
      # optional
  