anchor.diff:          '';
   
           type = types.submodule {
  -	  options = {
  +          options = {
               enable = mkOption {
                 type = types.bool;
                 default = false;
  
positive.code:                 will work only the first time.
                '';
              };
  	  };
          };
        };
  
  
negative.code: 
      assertions = [
        { assertion = cfg.autoLogin.enable -> cfg.autoLogin.user != null;
          message = ''
            SDDM auto-login requires services.xserver.displayManager.sddm.autoLogin.user to be set
          '';
        }
        { assertion = cfg.autoLogin.enable -> elem defaultSessionName dmcfg.session.names;
          message = ''
            SDDM auto-login requires that services.xserver.desktopManager.default and
            services.xserver.windowMananger.default are set to valid values. The current
            default session: ${defaultSessionName} is not valid.
          '';
        }
      ];
  
  