Extract counters if available (lazy).

        Looks for nscannedObjects or docsExamined.

def nscannedObjects(self):
        """
        Extract counters if available (lazy).

        Looks for nscannedObjects or docsExamined.
        """
        if not self._counters_calculated:
            self._counters_calculated = True
            self._extract_counters()

        return self._nscannedObjects