code: def AddEventData(self, event_data):
      
      self._RaiseIfNotWritable()
  
      event_data = self._PrepareAttributeContainer(event_data)
  
      identifier = event_data.GetIdentifier()
      lookup_key = identifier.CopyToString()
      self._event_data[lookup_key] = event_data
docs: Adds event data.
  
      Args:
        event_data (EventData): event data.
  
      Raises:
        IOError: when the storage writer is closed.
        OSError: when the storage writer is closed.