code: def _aggregate(self, instanceId, container, value, subKey = None):
      
  
      # Get the aggregator.
      if instanceId not in self._aggregators:
        self._aggregators[instanceId] = _Stats.getAggregator(instanceId, self.__name)
      aggregator = self._aggregators[instanceId]
  
      # If we are aggregating, get the old value.
      if aggregator:
        oldValue = container.get(self.__name)
        if subKey:
          oldValue = oldValue[subKey]
          aggregator[0].update(aggregator[1], oldValue, value, subKey)
        else:
          aggregator[0].update(aggregator[1], oldValue, value)
docs: Performs stat aggregation.