code: func totalBytesEstimate(tc *torrent.Client) (ret int64) {
  	var noInfo, hadInfo int64
  	for _, t := range tc.Torrents() {
  		info := t.Info()
  		if info == nil {
  			noInfo++
  			continue
  		}
  		ret += info.TotalLength()
  		hadInfo++
  	}
  	if hadInfo != 0 {
  		// Treat each torrent without info as the average of those with,
  		// rounded up.
  		ret += (noInfo*ret + hadInfo - 1) / hadInfo
  	}
  	return
  }
docs: // Returns an estimate of the total bytes for all torrents.