code: func pseudoRand() string {
  	ts := time.Now().UnixNano()
  	lastUsedTimeLock.Lock()
  	if ts <= lastUsedTime {
  		ts = lastUsedTime + 1
  	}
  	lastUsedTime = ts
  	lastUsedTimeLock.Unlock()
  
  	// Hash the state to get a smaller pseudorandom string.
  	h := sha256.New()
  	fmt.Fprintf(h, "%v_%v", os.Getpid(), ts)
  	sum := h.Sum(nil)
  	digest := base64.RawURLEncoding.EncodeToString(sum)
  	return digest[:12]
  }
docs: // pseudoRand returns "random enough" string that can be used in file system
  // paths of temp files.