code: func SetLogger(logger log_Logger) {
  	if raceDetector {
  		globalMutex.Lock()
  		defer globalMutex.Unlock()
  	}
  	globalLogger = logger
  }
docs: // RACE WARNING: There are known data races when logging, which are manually
  // silenced when the race detector is in use. These data races won't be
  // observed in typical use, because logging is supposed to be set up once when
  // the application starts. Having raceDetector as a constant, the compiler
  // should elide the locks altogether in actual use.
  // Specify the *log.Logger object where log messages should be sent to.