anchor.diff:          end),
   
       case Res of
  +        {ok, {}} -> undefined;
           {ok, {Doc}} -> mongo_tuple_to_record(Type, Doc);
           {failure, Reason} -> {error, Reason};
           {connection_failure, Reason} -> {error, Reason}
  
positive.code: 
  pack_value({{_, _, _}, {_, _, _}} = Val) ->
      datetime_to_now(Val);
  pack_value(V) -> V.
  
  %% Functions below copied from emongo <https://github.com/boorad/emongo>
  
negative.code:         true -> calendar:now_to_datetime(Value);
          false -> Value
      end;
  mongo_to_boss_value(_AttrName, [H|T], _) when is_integer(H) ->
      {integers, [H|T]};
  mongo_to_boss_value(AttrName, Value, _RecordType) ->
      case is_id_attr(AttrName) and (Value =/= "") of 
          true -> 
  