code: func randomSource() *rand.Rand {
  	bytes := make([]byte, 8)
  	seed := time.Now().UnixNano()
  	if _, err := crand.Read(bytes); err == nil {
  		seed = int64(binary.LittleEndian.Uint64(bytes))
  	}
  
  	src := rand.NewSource(seed)
  	return rand.New(src)
  }
docs: // randomSource returns a pseudo random value generator.