code: func (s *Session) AcceptStream() (*Stream, error) {
  	select {
  	case stream := <-s.acceptCh:
  		if err := stream.sendWindowUpdate(); err != nil {
  			return nil, err
  		}
  		return stream, nil
  	case <-s.shutdownCh:
  		return nil, s.shutdownErr
  	}
  }
docs: // AcceptStream is used to block until the next available stream
  // is ready to be accepted.