code: def _AddEventData(self, event_data):
      
      identifier = event_data.GetIdentifier()
      lookup_key = identifier.CopyToString()
  
      self._storage_writer.AddEventData(event_data)
  
      identifier = event_data.GetIdentifier()
      self._event_data_identifier_mappings[lookup_key] = identifier
docs: Adds event data.
  
      Args:
        event_data (EventData): event data.