code: func (dg *deliverGroup) ClientConnect(ctx context.Context, dc *deliverClient) {
  	defer dg.wg.Done()
  	df, err := dc.Client.DeliverFiltered(ctx)
  	if err != nil {
  		err = errors.WithMessage(err, fmt.Sprintf("error connecting to deliver filtered at %s", dc.Address))
  		dg.setError(err)
  		return
  	}
  	defer df.CloseSend()
  	dc.Connection = df
  
  	envelope := createDeliverEnvelope(dg.ChannelID, dg.Certificate)
  	err = df.Send(envelope)
  	if err != nil {
  		err = errors.WithMessage(err, fmt.Sprintf("error sending deliver seek info envelope to %s", dc.Address))
  		dg.setError(err)
  		return
  	}
  }
docs: // ClientConnect sends a deliver seek info envelope using the
  // provided deliver client, setting the deliverGroup's Error
  // field upon any error