glog.go
func (s *Severity) Set(value string) error {
	var threshold Severity
	// Is it a known name?
	if v, ok := severityByName(value); ok {
		threshold = v
	} else {
		v, err := strconv.Atoi(value)
		if err != nil {
			return err
		}
		threshold = Severity(v)
	}
	*s = threshold
	return nil
}
func (s *Severity) Set(value string) error {
	var threshold Severity
	// Is it a known name?
	if v, ok := severityByName(value); ok {
		threshold = v
	} else {
		v, err := strconv.Atoi(value)
		if err != nil {
			return err
		}
		threshold = Severity(v)
	}
	*s = threshold
	return nil
}
// Set is part of the flag.Value interface.