anchor.diff:  
     config = mkIf cfg.enable {
       # Prefer the config file over settings if both are set.
  -    services.corerad.configFile = mkDefault (writeTOML "corerad.toml" cfg.settings);
  +    services.corerad.configFile = mkDefault (settingsFormat.generate "corerad.toml" cfg.settings);
   
       systemd.services.corerad = {
         description = "CoreRAD IPv6 NDP RA daemon";
  
positive.code:     enable = mkEnableOption "CoreRAD IPv6 NDP RA daemon";
  
      settings = mkOption {
        type = types.uniq types.attrs;
        example = literalExample ''
          {
            interfaces = [
  
negative.code: 
  let
    cfg = config.services.corerad;
    settingsFormat = pkgs.formats.toml {};
  
  in {
    meta.maintainers = with maintainers; [ mdlayher ];
  