def purge_obsolete_samples(self, config, now):
        """
        Timeout any windows that have expired in the absence of any events
        """
        expire_age = config.samples * config.time_window_ms
        for sample in self._samples:
            if now - sample.last_window_ms >= expire_age:
                sample.reset(now)

        Timeout any windows that have expired in the absence of any events
        
kafka/metrics/stats/sampled_stat.py