log/logger.go
func (l *Logger) Fatalf(format string, args ...interface{}) {
	l.Output(2, LevelFatal, fmt.Sprintf(format, args...))
	os.Exit(1)
}
func (l *Logger) Fatalf(format string, args ...interface{}) {
	l.Output(2, LevelFatal, fmt.Sprintf(format, args...))
	os.Exit(1)
}
// Fatalf records the log with fatal level and exits