anchor.diff:  strip_fields([#'Field'{name = N, value = {null, _}} | Rest], Acc) ->
       strip_fields(Rest, [{N, undefined} | Acc]);
   strip_fields([#'Field'{name = N, value = {_, V}} | Rest], Acc) ->
  -    strip_fields(Rest, [{N, V} | Acc]).
  +    strip_fields(Rest, [{N, V} | Acc]);
  +strip_fields([], Acc) ->
  +    lists:reverse(Acc).
   
   -spec validate_attributes(Attr :: [string()], Acc :: [atom()]) ->
       [atom()].
  
positive.code: 
  -spec strip_fields(Fields :: [#'Field'{}]) ->
      [{string(), term()}].
      strip_fields(Fields) ->
          strip_fields(Fields, []).
  
  -spec strip_fields(Fields :: [#'Field'{}],
  		   Acc :: [{string(), term()}]) ->
      [{string(), term()}].
  strip_fields([], Acc) ->
      lists:reverse(Acc);
  strip_fields([#'Field'{name = N, value = {boolean, B}} | Rest], Acc) ->
      Bool =
  	case B of
  
negative.code: 	    {binary, list_to_binary(V)}
      end;
  make_value(undefined) ->
      {null, <<>>};
  make_value(A) when is_atom(A) ->
      {string, atom_to_list(A)};
  make_value(T) when is_tuple(T) ->
  