code: func loadClientDigests(path string) (*digests.ClientDigestsFile, error) {
  	switch f, err := os.Open(path); {
  	case os.IsNotExist(err):
  		base := filepath.Base(path)
  		return nil, fmt.Errorf("the file with pinned client hashes (%s) doesn't exist, "+
  			"use 'cipd selfupdate-roll -version-file %s' to generate it",
  			base, strings.TrimSuffix(base, digestsSfx))
  	case err != nil:
  		return nil, err
  	default:
  		defer f.Close()
  		return digests.ParseClientDigestsFile(f)
  	}
  }
docs: // loadClientDigests loads the *.digests file with client binary hashes.