code: def addValue(self, _, value):
      
      if value is not None:
        try:
          self._count += self._dataFormat.getCount(value)
          self._total += self._dataFormat.getValue(value) * self._dataFormat.getCount(value)
        except TypeError:
          self._count += 1
          self._total += value
docs: Adds a value from the given source.