code: func (bs *Bootstrap) GetViewerURLForStreams(streams ...streamclient.Stream) (string, error) {
  	if bs.Prefix == "" {
  		return "", errors.New("no prefix is configured")
  	}
  
  	paths := make([]types.StreamPath, len(streams))
  	for i, s := range streams {
  		paths[i] = bs.Prefix.Join(types.StreamName(s.Properties().Name))
  	}
  	return bs.GetViewerURL(paths...)
  }
docs: // GetViewerURLForStreams returns a log stream viewer URL to the aggregate set
  // of supplied streams.
  //
  // If the any of the Prefix, Project, or CoordinatorHost values is not
  // populated, an error will be returned.