code: func parseDuration(s string) (time.Duration, error) {
  	if s == "" {
  		return time.Duration(-1), nil
  	}
  
  	b, err := strconv.ParseBool(s)
  
  	switch {
  	case err != nil:
  		return time.ParseDuration(s)
  	case b:
  		return time.Duration(-1), nil
  	}
  
  	return time.Duration(0), nil
  }
docs: // parseDuration converts the given string s to a duration value.
  // If it is empty string or a true boolean value according to strconv.ParseBool, a negative duration is returned.
  // If the boolean value is false, a 0 duration is returned.
  // If the string s is a duration value, then it is returned.
  // It returns an error if the duration conversion failed.