anchor.diff:                home = "/home/alice";
                 createHome = true;
                 useDefaultShell = true;
  +              password = "foobar";
               };
   
             environment.systemPackages = [ pkgs.xorg.xclock pkgs.xorg.xwd ];
  
positive.code:         { config, pkgs, ... }:
  
          { services.xserver.enable = true;
            services.xserver.desktopManager.default = "kde4";
            services.xserver.desktopManager.kde4.enable = true;
  
            users.extraUsers = pkgs.lib.singleton
              { name = "alice";
  
negative.code: 
        $client->waitForFile("/tmp/.X11-unix/X0");
  
        sleep 60;
  
        print STDERR $client->execute("DISPLAY=:0.0 xwd -root > /hostfs/$ENV{out}/screen.xwd");
      '';
  