code: func (m *Multiplex) Accept() (*Stream, error) {
  	select {
  	case s, ok := <-m.nstreams:
  		if !ok {
  			return nil, errors.New("multiplex closed")
  		}
  		return s, nil
  	case <-m.closed:
  		return nil, m.shutdownErr
  	}
  }
docs: // Accept accepts the next stream from the connection.