anchor.diff:                text = "Invalid value for option \"simple_structs\": "
                 "it must be a boolean"
               };
  +        {node_mods, _} ->
  +            Error#yaml_invalid_option{
  +              text = "Invalid value for option \"node_mods\": "
  +              "it must be a list of modules"
  +            };
           _ ->
               yaml_errors:format(Error, "Unknown option \"~w\"", [Option])
       end,
  
positive.code: 
  is_option_valid({simple_structs, Flag}) when is_boolean(Flag) ->
      true;
  is_option_valid(_) ->
      false.
  
  
negative.code:     },
      return_new_fun(Repr1).
  
  umerge_unsorted(List1, List2) ->
      Fun = fun(Mod, List) ->
          case lists:member(Mod, List) of
              true  -> List;
              false -> List ++ [Mod]
          end
      end,
      lists:foldl(Fun, List1, List2).
  
  filter_autodetection_capable_mods([Mod | Rest], Auto) ->
      Auto1 = case erlang:function_exported(Mod, try_construct_token, 3) of
          true  -> [Mod | Auto];
          false -> Auto
      end,
      filter_autodetection_capable_mods(Rest, Auto1);
  filter_autodetection_capable_mods([], Auto) ->
      lists:reverse(Auto).
  
  index_tags([Mod | Rest], Tags) ->
  