def getSilent(self):
        """Return a list of clients with heartbeat older than CHECK_TIMEOUT"""
        limit = time.time() - CHECK_TIMEOUT
        self._lock.acquire()
        silent = [ip for (ip, ipTime) in self.items() if ipTime < limit]
        self._lock.release()
        return silent
Return a list of clients with heartbeat older than CHECK_TIMEOUT
recipes/Python/52302_PyHeartbeat__detecting_inactive/recipe-52302.py