def FreezeTimestamp(self):
    self.prev_frozen_timestamps.append(self.frozen_timestamp)
    self.frozen_timestamp = rdfvalue.RDFDatetime().Now()
A basic interface around both queue and send_now. This honors a global
dataset/ETHPy150Open google/grr/grr/lib/queue_manager.py/QueueManager.FreezeTimestamp--crossover with--dataset/ETHPy150Open davemerwin/blue-channel/external_apps/notification/models.py/send