anchor.diff:  
     cfg = config.services.emacs;
   
  -in
  -
  -{
  +in {
     options = {
       services.emacs = {
         enable = mkOption {
  
positive.code:         description = "This option specifies the emacs package to use.";
        };
  
        exec = mkOption {
          type = types.str;
          default = "emacs";
  
negative.code:   config = mkIf cfg.enable {
  
      launchd.user.agents.emacs = {
        path = cfg.additionalPath ++ [ config.environment.systemPath ];
        serviceConfig.ProgramArguments =
          [ "${cfg.package}/bin/${cfg.exec}" "--fg-daemon" ];
        serviceConfig.RunAtLoad = true;
      };
  
  