anchor.diff:      default = null;
     });
   
  -  mkBrewfileLineOption = mkOption {
  -    type = types.nullOr types.str;
  +  mkInternalOption = args: mkOption (args // {
       visible = false;
       internal = true;
       readOnly = true;
  -  };
  +  });
   
     mkProcessedSubmodConfig = attrs: mapAttrs (_: mkBrewfileLineValueString)
       (filterAttrsRecursive (n: v: n != "_module" && n != "brewfileLine" && v != null) attrs);
  
positive.code:         '';
        };
  
        brewfileLine = mkBrewfileLineOption;
      };
  
      config =
  
negative.code:         '';
        };
  
        brewfileLine = mkInternalOption { type = types.nullOr types.str; };
      };
  
      config =
  