code: func NewReader(r io.Reader) (*Reader, error) {
  	zlib, err := zlib.NewReader(r)
  	if err != nil {
  		return nil, packfile.ErrZLib.AddDetails(err.Error())
  	}
  
  	return &Reader{
  		zlib: zlib,
  	}, nil
  }
docs: // NewReader returns a new Reader reading from r.