anchor.diff:  
   { lib, ... }:
   
  +let
  +  inherit (lib) types;
  +in
   {
     options = {
   
  
positive.code:       description = ''
          The user IDs used in NixOS.
        '';
      };
  
      ids.gids = lib.mkOption {
  
negative.code:       description = ''
          The group IDs used in NixOS.
        '';
        type = types.attrsOf types.int;
      };
  
    };
  