anchor.diff:  
   -spec rm_fields(Json::json(), [Field::field()]) -> json_output_value().
   rm_fields(Json, Fields) ->
  -    Fun = fun(Attr, Acc) -> rm_field(Acc, Attr) end,
  -    lists:foldl(Fun, Json, Fields).
  +    Fun = fun(Attr, Acc) -> rm_field(Acc, parse_attr(Attr)) end,
  +    format_output(lists:foldl(Fun, parse_json(Json), Fields)).
   
   %% @doc
   %% Sets a json attribute 'Attr' to 'Value'. This function is only for creating 
  
positive.code: %% @hidden
  %% Function: parse_value/1
  %% @end
  parse_value([]) ->
      [];
  parse_value({s, Value}) ->
      binary:list_to_bin(Value);
  parse_value(Value) when is_tuple(Value)->
      erlson:from_json_term(Value);
  parse_value(Value) when is_list(Value) ->
  
negative.code: %% ====================================================================
  -export([add_value/3,
  	 add_values/2,
  	 convert_undefined/1,
  	 decode/1, 
  	 encode/1, 
  	 field_value_exists/3, 
  