code: func openReader(name string) (*ReadCloser, error) {
  	tr, f, err := openFile(name)
  	if err != nil {
  		return nil, err
  	}
  
  	r := new(ReadCloser)
  	if err := r.init(tr); err != nil {
  		return nil, err
  	}
  	r.f = f
  	return r, nil
  }
docs: // openReader opens the tar.gz file specified by name and return a tar.Reader.