anchor.diff: -{
  -  alsa-lib,
  -  autoPatchelfHook,
  -  callPackage,
  -  fetchzip,
  -  gnome2,
  -  gtk2,
  -  gtk3,
  -  lib,
  -  mesa,
  -  nss,
  -  stdenv,
  -  udev,
  -  unzip,
  -  wrapGAppsHook,
  -  xorg,
  +{ alsa-lib
  +, autoPatchelfHook
  +, callPackage
  +, fetchzip
  +, gnome2
  +, gtk2
  +, gtk3
  +, lib
  +, mesa
  +, nss
  +, stdenv
  +, udev
  +, unzip
  +, wrapGAppsHook
  +, xorg
   }:
   
   stdenv.mkDerivation rec {
  
positive.code:   nativeBuildInputs = [ autoPatchelfHook wrapGAppsHook unzip ];
  
    buildInputs = with xorg; [
      libXScrnSaver libXdamage libXtst libxshmfence
    ] ++ [
      nss gtk2 alsa-lib gnome2.GConf gtk3
      mesa # for libgbm
    ];
  
  
negative.code:     updateScript = ./update.sh;
  
      tests = {
        example = callPackage ./cypress-example-kitchensink { };
      };
    };
  
  