anchor.diff:          description = "Output gamma configuration.";
           default = "";
           example = "1.0:0.909:0.833";
  +      };
  +
  +      rotate = mkOption {
  +        type = types.nullOr (types.enum ["normal" "left" "right" "inverted"]);
  +        description = "Output rotate configuration.";
  +        default = null;
  +        example = "left";
         };
       };
     };
  
positive.code:                   mode = "3840x2160";
                    gamma = "1.0:0.909:0.833";
                    rate = "60.00";
                  };
                };
                hooks.postswitch = readFile ./work-postswitch.sh;
  
negative.code:     ${optionalString (config.gamma != "") "gamma ${config.gamma}"}
      ${optionalString (config.mode != "") "mode ${config.mode}"}
      ${optionalString (config.rate != "") "rate ${config.rate}"}
      ${optionalString (config.rotate != null) "rotate ${config.rotate}"}
    '' else ''
      output ${name}
      off
  