code: def _get_initial_request(self):
          
          # Any ack IDs that are under lease management need to have their
          # deadline extended immediately.
          if self._leaser is not None:
              # Explicitly copy the list, as it could be modified by another
              # thread.
              lease_ids = list(self._leaser.ack_ids)
          else:
              lease_ids = []
  
          # Put the request together.
          request = types.StreamingPullRequest(
              modify_deadline_ack_ids=list(lease_ids),
              modify_deadline_seconds=[self.ack_deadline] * len(lease_ids),
              stream_ack_deadline_seconds=self.ack_histogram.percentile(99),
              subscription=self._subscription,
          )
  
          # Return the initial request.
          return request
docs: Return the initial request for the RPC.
  
          This defines the initial request that must always be sent to Pub/Sub
          immediately upon opening the subscription.
  
          Returns:
              google.cloud.pubsub_v1.types.StreamingPullRequest: A request
              suitable for being the first request on the stream (and not
              suitable for any other purpose).