anchor.diff:    version = "unstable-2020-04-02";
     # python setup.py --version
     realVersion = "0.2.dev49+g${lib.substring 0 7 src.rev}";
  +  disabled = pythonOlder "3.6";
   
     src = fetchFromGitHub {
       owner = "nmigen";
  
positive.code:     sha256 = "sha256-3+mxHyg0a92/BfyePtKT5Hsk+ra+fQzTjCJ2Ech44/s=";
    };
  
    disabled = pythonOlder "3.6";
  
    nativeBuildInputs = [ setuptools_scm ];
  
    propagatedBuildInputs = [ setuptools pyvcd jinja2 ];
  
    checkInputs = [ yosys symbiyosys yices ];
  
    preBuild = ''
      export SETUPTOOLS_SCM_PRETEND_VERSION="${realVersion}"
    '';
  
    meta = with lib; {
      description = "A refreshed Python toolbox for building complex digital hardware";
  
negative.code: , jinja2
  
  # for tests
  , pytestCheckHook
  , yosys
  , symbiyosys
  , yices
  