code: func openStat(fs http.FileSystem, name string) (http.File, os.FileInfo, error) {
  	f, err := fs.Open(name)
  	if err != nil {
  		return nil, nil, err
  	}
  	fi, err := f.Stat()
  	if err != nil {
  		f.Close()
  		return nil, nil, err
  	}
  	return f, fi, nil
  }
docs: // openStat performs Open and Stat and returns results, or first error encountered.
  // The caller is responsible for closing the returned file when done.