anchor.diff:          message = "serverAddr should be set if role is 'agent'";
         }
         {
  -        assertion = cfg.role == "agent" -> cfg.token != "";
  -        message = "token should be set if role is 'agent'";
  +        assertion = cfg.role == "agent" -> cfg.token != "" || cfg.tokenFile != null;
  +        message = "token or tokenFile should be set if role is 'agent'";
         }
       ];
   
  
positive.code: 
      token = mkOption {
        type = types.str;
        description = "The k3s token to use when connecting to the server. This option only makes sense for an agent.";
        default = "";
      };
  
      docker = mkOption {
  
negative.code:             "${cfg.package}/bin/k3s ${cfg.role}"
            ] ++ (optional cfg.docker "--docker")
            ++ (optional cfg.disableAgent "--disable-agent")
            ++ (optional (cfg.role == "agent") "--server ${cfg.serverAddr} ${
              if cfg.tokenFile != null then
                "--token-file ${cfg.tokenFile}"
              else
                "--token ${cfg.token}"
            }")
            ++ [ cfg.extraFlags ]
          );
        };
  