anchor.diff:      F = fun({KeyPartsReversed, Value}) ->
           KeyParts = lists:reverse(KeyPartsReversed),
           Key = string:join(KeyParts, "."),
  -        { Key, Value }
  +        { Key, wf:to_list(Value) }
       end,
       lists:map(F, Params).
   
  
positive.code: %%   Path   = [b, c]
  %%   Params = [y, b, c]
  refine_params([], Params) -> 
      [V || {_, V} <- Params];
  refine_params([H|T], Params) ->
      F = fun({Path, Value}, Acc) ->
          case split_on(H, Path) of
  
negative.code: get_value(Path, Config, State) ->
      case get_values(Path, Config, State) of
          [] -> undefined;
          [One] -> wf:to_list(One);
          _Many -> throw({?MODULE, too_many_matches, Path})
      end.
  
  