anchor.diff:  
     ###### implementation
   
  -  config = mkIf cfg.enable
  -    (mkAssert (!(cfg.startOpenSSHAgent && cfg.startGnuPGAgent))
  -      ''
  -        The OpenSSH agent and GnuPG agent cannot be started both.
  -        Choose between `startOpenSSHAgent' and `startGnuPGAgent'.
  -      ''
  -  {
  +  config = mkIf cfg.enable (checkAgent (checkPolkit {
   
       boot.extraModulePackages =
         optional (elem "nvidia" driverNames) kernelPackages.nvidia_x11 ++
  
positive.code:     monitors = foldl mkMonitor [] xrandrHeads;
    in concatMapStrings (getAttr "value") monitors;
  
    configFile = pkgs.stdenv.mkDerivation {
      name = "xserver.conf";
  
  
negative.code:         ${xrandrMonitorSections}
        '';
  
    }));
  
  }
  