code: def make_event_data(self, flavor, data):
          
          if not flavor.startswith('_'):
              raise ValueError('Event flavor must start with _underscore')
  
          d = {'source': {'space': self._event_space, 'id': self._source_id}}
          d.update(data)
          return {flavor: d}
docs: Marshall ``flavor`` and ``data`` into a standard event.