code: func (l *Log) Fatal(args ...interface{}) {
  	opts := getLoggerOpts(l.module, api.CRITICAL)
  	if l.loadCustomLogger() {
  		l.customLogger.Fatal(args...)
  		return
  	}
  	l.log(opts, api.CRITICAL, args...)
  	l.deflogger.Fatal(args...)
  }
docs: // Fatal is CRITICAL log followed by a call to os.Exit(1).