anchor.diff:        pyyaml
         setuptools
       ]))
  -  ]
  -    ++ optionals eventGUISupport [ cairo glib gtk3 ];
  +  ] ++ lib.optionals eventGUISupport [ cairo glib gtk3 ];
   
     checkInputs = [
       check
  
positive.code: { lib, stdenv, fetchFromGitLab, pkg-config, meson, ninja
  , libevdev, mtdev, udev, libwacom
  , documentationSupport ? false, doxygen ? null, graphviz ? null # Documentation
  , eventGUISupport ? false, cairo ? null, glib ? null, gtk3 ? null # GUI event viewer support
  , testsSupport ? false, check ? null, valgrind ? null, python3 ? null
  }:
  
  assert documentationSupport -> doxygen != null && graphviz != null && python3 != null;
  assert eventGUISupport -> cairo != null && glib != null && gtk3 != null;
  assert testsSupport -> check != null && valgrind != null && python3 != null;
  
  let
    mkFlag = optSet: flag: "-D${flag}=${lib.boolToString optSet}";
  
negative.code:   ];
  
    nativeBuildInputs = [ pkg-config meson ninja ]
      ++ lib.optionals documentationSupport [ doxygen graphviz sphinx-build ];
  
    buildInputs = [
      libevdev
  