anchor.diff:          Section "InputDevice"
             Driver "wacom"
             Identifier "Wacom_stylus"
  -          Option "Device" "${cfg.device}"
  +          ${optionalString (cfg.device != null) ''
  +            Option "Device" "${cfg.device}"
  +          ''}
             Option "Type" "stylus"
             ${optionalString (cfg.forceDeviceType != null) ''
               Option "ForceDevice" "${cfg.forceDeviceType}"
             ''}
  -          Option "Button2" "3"
  +          ${cfg.stylusExtraConfig}
           EndSection
   
           Section "InputDevice"
             Driver "wacom"
             Identifier "Wacom_eraser"
  -          Option "Device" "${cfg.device}"
  +          ${optionalString (cfg.device != null) ''
  +            Option "Device" "${cfg.device}"
  +          ''}
             Option "Type" "eraser"
             ${optionalString (cfg.forceDeviceType != null) ''
               Option "ForceDevice" "${cfg.forceDeviceType}"
             ''}
  -          Option "Button1" "2"
  +          ${cfg.eraserExtraConfig}
           EndSection
   
           Section "InputDevice"
             Driver "wacom"
             Identifier "Wacom_cursor"
  -          Option "Device" "${cfg.device}"
  +          ${optionalString (cfg.device != null) ''
  +            Option "Device" "${cfg.device}"
  +          ''}
             Option "Type" "cursor"
             ${optionalString (cfg.forceDeviceType != null) ''
               Option "ForceDevice" "${cfg.forceDeviceType}"
             ''}
  +          ${cfg.cursorExtraConfig}
           EndSection
         '';
   
  
positive.code:     services.xserver.serverLayoutSection =
        ''
          InputDevice "Wacom_stylus"
          InputDevice "Wacom_cursor"
          InputDevice "Wacom_eraser"
        '';
  
      services.xserver.config =
  
negative.code: 
        enable = mkOption {
          default = false;
          description = "Whether to enable the Wacom touchscreen/digitizer/tablet.";
        };
  
        device = mkOption {
          default = null;
          example = "/dev/ttyS0";
          description = "Device to use. Set to null for autodetect (think USB tablet).";
        };
  
        forceDeviceType = mkOption {
          default = null;
          example = "ISDV4";
          description = "Some models (think touchscreen) require the device type to be specified. Set to null for autodetect (think USB tablet).";
        };
  
        stylusExtraConfig = mkOption {
          default = "";
          example = ''
              Option "Button1" "2"
            '';
          description = "Lines to be added to Wacom_stylus InputDevice section.";
        };
  
        eraserExtraConfig = mkOption {
          default = "";
          example = ''
              Option "Button2" "3"
            '';
          description = "Lines to be added to Wacom_eraser InputDevice section.";
        };
  
        cursorExtraConfig = mkOption {
          default = "";
          example = "";
          description = "Lines to be added to Wacom_cursor InputDevice section.";
        };
  
      };
  