code: func (ch *Chunk) Read(p []byte) (n int, err error) {
  	if ch == nil || ch.R == nil {
  		return 0, errors.New("nil chunk/reader pointer")
  	}
  	n, err = ch.R.Read(p)
  	ch.Pos += n
  	return n, err
  }
docs: // Read implements the reader interface