anchor.diff:  
     config = mkIf cfg.enable {
   
  -    users.extraUsers = singleton
  +    users.extraUsers = mkIf (cfg.user == null) [
         { name = cfg.user;
           description = "Quassel IRC client daemon";
  -      };
  +      }];
       
   
       jobs.quassel =
  
positive.code:       };
  
        dataDir = mkOption {
          default = ''/home/${cfg.user}/.config/quassel-irc.org'';
          description = ''
            The directory holding configuration files, the SQlite database and the SSL Cert.
          '';
        };
  
        user = mkOption {
          default = "quassel";
          description = ''
            The user the Quassel daemon should run as.
          '';
        };
  
  
negative.code: let
    quassel = pkgs.quasselDaemon;
    cfg = config.services.quassel;
    user = if cfg.user != null then cfg.user else "quassel";
  in
  
  {
  