code: func HashKey(parts ...string) string {
  	hash := sha256.New()
  	bio := bufio.NewWriter(hash)
  
  	// Add a full NULL-delimited key sequence segment to our hash.
  	for i, part := range parts {
  		// Write the separator, except for the first key.
  		if i > 0 {
  			if _, err := bio.WriteRune('\x00'); err != nil {
  				panic(err)
  			}
  		}
  
  		if _, err := bio.WriteString(part); err != nil {
  			panic(err)
  		}
  	}
  	if err := bio.Flush(); err != nil {
  		panic(err)
  	}
  
  	// Return the hex-encoded hash sum.
  	return hex.EncodeToString(hash.Sum(nil))
  }
docs: // HashKey composes a hex-encoded SHA256 string from the supplied parts. The
  // local schema version and KeyType are included in the hash.