code: def add_sample(self, value, timestamp, attachments):
          
          self._count_data += 1
          bucket = self.increment_bucket_count(value)
  
          if attachments is not None and self.exemplars is not None:
              self.exemplars[bucket] = Exemplar(value, timestamp, attachments)
          if self.count_data == 1:
              self._mean_data = value
              return
  
          old_mean = self._mean_data
          self._mean_data = self._mean_data + (
              (value - self._mean_data) / self._count_data)
          self._sum_of_sqd_deviations = self._sum_of_sqd_deviations + (
              (value - old_mean) * (value - self._mean_data))
docs: Adding a sample to Distribution Aggregation Data