anchor.diff:          default = null;
           description = ''
             User account under which Klipper runs.
  +
             If null is specified (default), a temporary user will be created by systemd.
           '';
         };
  
positive.code:         '';
        };
  
        firmware = mkOption {
          description = "Firmwares klipper should manage";
          default = { };
          type = with types; attrsOf
  
negative.code:             mcu = lib.strings.sanitizeDerivationName mcu;
              inherit firmwareConfig;
            })
            cfg.firmwares;
          firmwareFlasher = mapAttrsToList
            (mcu: firmware: pkgs.callPackage pkgs.klipper-flash.override {
              mcu = lib.strings.sanitizeDerivationName mcu;
              klipper-firmware = firmware;
              flashDevice = cfg.settings."${mcu}".serial;
              firmwareConfig = cfg.firmwares."${mcu}".firmwareConfig;
            })
            firmwares;
        in
  