code: func GetCommentHeader(in io.Reader) (vorbis.CommentHeader, error) {
  	var dec vorbis.Decoder
  	r := oggReader{source: in}
  	for i := 0; i < 2; i++ {
  		p, err := r.NextPacket()
  		if err != nil {
  			return vorbis.CommentHeader{}, err
  		}
  		err = dec.ReadHeader(p)
  		if err != nil {
  			return vorbis.CommentHeader{}, err
  		}
  	}
  	return dec.CommentHeader, nil
  }
docs: // GetCommentHeader returns a struct containing info from the comment header.