code: def AddEventTags(self, event_tags):
      
      self._RaiseIfNotWritable()
  
      for event_tag in event_tags:
        self.AddEventTag(event_tag)
docs: Adds event tags.
  
      Args:
        event_tags (list[EventTag]): event tags.
  
      Raises:
        IOError: when the storage file is closed or read-only or
            if the event tags cannot be serialized.
        OSError: when the storage file is closed or read-only or
            if the event tags cannot be serialized.