code: func CheckSignal(rawSignal string) error {
  	s, err := strconv.Atoi(rawSignal)
  	if err == nil {
  		if s == 0 {
  			return fmt.Errorf("Invalid signal: %s", rawSignal)
  		}
  		return nil
  	}
  	if _, ok := SignalMap[strings.TrimPrefix(strings.ToUpper(rawSignal), "SIG")]; !ok {
  		return fmt.Errorf("Invalid signal: %s", rawSignal)
  	}
  	return nil
  }
docs: // CheckSignal translates a string to a valid syscall signal.
  // It returns an error if the signal map doesn't include the given signal.