code: func deriveRevision(c *scannedConfigs) string {
  	keys := make([]string, 0, len(c.contentHashMap))
  	for k := range c.contentHashMap {
  		keys = append(keys, k)
  	}
  	sort.Strings(keys)
  	hsh := sha256.New()
  	for _, k := range keys {
  		fmt.Fprintf(hsh, "%s\n%s\n", k, c.contentHashMap[k])
  	}
  	digest := hsh.Sum(nil)
  	return hex.EncodeToString(digest[:])[:40]
  }
docs: // deriveRevision generates a revision string from data in contentHashMap.