code: func (o Output) Digests() map[string]string {
  	out := make(map[string]string, len(o.Data))
  	for file, body := range o.Data {
  		out[file] = hex.EncodeToString(blobDigest(body))
  	}
  	return out
  }
docs: // Digests returns a map "file name -> hex SHA256 of its body".