code: func (t *Torrent) BytesCompleted() int64 {
  	t.cl.rLock()
  	defer t.cl.rUnlock()
  	return t.bytesCompleted()
  }
docs: // Number of bytes of the entire torrent we have completed. This is the sum of
  // completed pieces, and dirtied chunks of incomplete pieces. Do not use this
  // for download rate, as it can go down when pieces are lost or fail checks.
  // Sample Torrent.Stats.DataBytesRead for actual file data download rate.