code: func ID(bits int) (string, error) {
  	if math.Mod(float64(bits), 8) != 0 {
  		return "", errors.New("Given bits should be a multiple of 8")
  	}
  
  	b := make([]byte, bits/8)
  	if _, err := rand.Read(b); err != nil {
  		return "", err
  	}
  
  	return base64.RawURLEncoding.EncodeToString(b), nil
  }
docs: // ID generates a base64 encoded URL safe unique ID using crypto/rand.
  // This is a cryptographically secure pseudorandom number presented
  // as an unpadded base64 encoded string.
  //
  // 'bits' should be a multiple of 8.
  // Lenght of generated string will be ceiling(bits * 4 / 24)