code: def _get_event_request_header(self):
          
          otr_status = (hangouts_pb2.OFF_THE_RECORD_STATUS_OFF_THE_RECORD
                        if self.is_off_the_record else
                        hangouts_pb2.OFF_THE_RECORD_STATUS_ON_THE_RECORD)
          return hangouts_pb2.EventRequestHeader(
              conversation_id=hangouts_pb2.ConversationId(id=self.id_),
              client_generated_id=self._client.get_client_generated_id(),
              expected_otr=otr_status,
              delivery_medium=self._get_default_delivery_medium(),
          )
docs: Return EventRequestHeader for conversation.