anchor.diff:    cfg = config.services.psd;
   
     configFile = ''
  -    ${if cfg.users != [ ] then ''
  +    ${optionalString (cfg.users != [ ]) ''
         USERS="${concatStringsSep " " cfg.users}"
  -    '' else ""}
  +    ''}
   
  -    ${if cfg.browsers != [ ] then ''
  +    ${optionalString (cfg.browsers != [ ]) ''
         BROWSERS="${concatStringsSep " " cfg.browsers}"
  -    '' else ""}
  +    ''}
   
       ${optionalString (cfg.volatile != "") "VOLATILE=${cfg.volatile}"}
       ${optionalString (cfg.daemonFile != "") "DAEMON_FILE=${cfg.daemonFile}"}
     '';
  +
   in {
  +
     options.services.psd = with types; {
       enable = mkOption {
         type = bool;
  
positive.code:   };
  
    config = mkIf cfg.enable {
  
      systemd = {
        services = {
          psd = {
  
negative.code:       };
  
        timers.psd-resync = {
          description = "Timer for profile sync daemon - ${cfg.resyncTimer}";
          partOf = [ "psd-resync.service" "psd.service" ];
  
          timerConfig = {
  