anchor.diff:  
     config = mkIf (config.services.xserver.enable && enabled) {
   
  +    boot.blacklistedKernelModules = [
  +      "nouveau"
  +      "nvidiafb"
  +      "rivafb"
  +      "rivatv"
  +    ];
  +
  +    boot.extraModulePackages = [
  +      nvidia-drivers
  +    ];
  +
  +    environment.etc."OpenCL/vendors/nvidia.icd".source =
  +      "${nvidia-drivers}/etc/OpenCL/vendors/nvidia.icd";
  +    environment.etc."nvidia/nvidia-application-profiles-rc.d".source =
  +      "${nvidia-drivers}/etc/nvidia/nvidia-application-profiles-rc.d";
  +
  +    environment.systemPackages = [
  +      nvidia-drivers
  +    ];
  +
  +    hardware.opengl.package = nvidia-drivers;
  +    hardware.opengl.package32 = nvidia-drivers_libs32;
  +
  +    services.acpid.enable = true;
  +
  +    # Create /dev/nvidia-uvm when the nvidia-uvm module is loaded.
  +    services.udev.extraRules = optionalString nvidia-drivers.cudaUVM ''
  +      KERNEL=="nvidia_uvm", RUN+="${pkgs.stdenv.shell} -c 'mknod -m 666 /dev/nvidia-uvm c $(grep nvidia-uvm /proc/devices | cut -d \  -f 1) 0'"
  +    '';
  +
       services.xserver.drivers = singleton {
         name = "nvidia";
         modules = [
  +        # x11glvnd module
  +        pkgs.libglvnd
           nvidia-drivers
         ];
         libPath = [
  
positive.code:       Option "RandRRotation" "on"
      '';
  
      hardware.opengl.package = nvidia-drivers;
      hardware.opengl.package32 = nvidia-drivers_libs32;
  
      environment.systemPackages = [
        nvidia-drivers
      ];
  
      boot.extraModulePackages = [
        nvidia-drivers
      ];
  
      boot.kernelModules = [
        # nvidia-uvm is required by CUDA applications.
        "nvidia-uvm"
      ];
  
      # Create /dev/nvidia-uvm when the nvidia-uvm module is loaded.
      services.udev.extraRules = ''
        KERNEL=="nvidia_uvm", RUN+="${pkgs.stdenv.shell} -c 'mknod -m 666 /dev/nvidia-uvm c $(grep nvidia-uvm /proc/devices | cut -d \  -f 1) 0'"
      '';
  
      boot.blacklistedKernelModules = [
        "nouveau"
        "nvidiafb"
      ];
  
      services.acpid.enable = true;
  
      environment.etc."OpenCL/vendors/nvidia.icd".source = "${nvidia-drivers}/etc/OpenCL/vendors/nvidia.icd";
  
    };
  
  }
  
negative.code: 
  { config, lib, pkgs, pkgs_i686, ... }:
  
  with {
    inherit (lib)
      elem
      mkIf
      optionals
      optionalString
      singleton;
  };
  
  let
  
  