code: def do_transform(self):
          
          if not self.transform:
              return
          try:
              self.latest_value = utils.Transform(
                  expr=self.transform, value=self.latest_value,
                  timedelta=self.time_between_updates().total_seconds()).result()
          except (TypeError, ValueError):
              logger.warn("Invalid transformation '%s' for metric %s",
                          self.transfrom, self.pk)
          self.transform = ''
docs: Apply the transformation (if it exists) to the latest_value