anchor.diff:  
     config = mkIf cfg.enable {
       boot.blacklistedKernelModules = [ "nvidia-drm" "nvidia" "nouveau" ];
  -    boot.kernelModules = optional cfg.bbswitch [ "bbswitch" ];
  -    boot.extraModulePackages = optional cfg.bbswitch kernel.bbswitch ++ optional useNvidia kernel.nvidia_x11;
  +    boot.kernelModules = optional useBbswitch [ "bbswitch" ];
  +    boot.extraModulePackages = optional useBbswitch kernel.bbswitch ++ optional useNvidia kernel.nvidia_x11;
   
       environment.systemPackages = [ bumblebee primus ];
   
  
positive.code:       wantedBy = [ "multi-user.target" ];
        before = [ "display-manager.service" ];
        serviceConfig = {
          ExecStart = "${bumblebee}/bin/bumblebeed --use-syslog -g ${cfg.group} --driver ${cfg.driver}";
        };
      };
    };
  
negative.code:         '';
        };
  
        pmMethod = mkOption {
          default = "auto";
          type = types.enum [ "auto" "bbswitch" "nouveau" "switcheroo" "none" ];
          description = ''
            Set preferred power management method for unused card.
          '';
        };
  
  