def UnfreezeTimestamp(self):
    if not self.prev_frozen_timestamps:
      raise RuntimeError("Unbalanced UnfreezeTimestamp call.")
    self.frozen_timestamp = self.prev_frozen_timestamps.pop()
Visit all fields in the message and replace episode fields with event fields.
dataset/ETHPy150Open google/grr/grr/lib/queue_manager.py/QueueManager.UnfreezeTimestamp--crossover with--dataset/ETHPy150Open viewfinderco/viewfinder/backend/base/message.py/RenameEventMigrator.MigrateBackward