code: def from_rollup_json(cls, stream, json_data):
          
          dp = cls.from_json(stream, json_data)
  
          # Special handling for timestamp
          timestamp = isoformat(dc_utc_timestamp_to_dt(int(json_data.get("timestamp"))))
  
          # Special handling for data, all rollup data is float type
          type_converter = _get_decoder_method(stream.get_data_type())
          data = type_converter(float(json_data.get("data")))
  
          # Update the special fields
          dp.set_timestamp(timestamp)
          dp.set_data(data)
          return dp
docs: Rollup json data from the server looks slightly different
  
          :param DataStream stream: The :class:`~DataStream` out of which this data is coming
          :param dict json_data: Deserialized JSON data from Device Cloud about this device
          :raises ValueError: if the data is malformed
          :return: (:class:`~DataPoint`) newly created :class:`~DataPoint`