code: func Set(logger Logger) (err error) {
  	if _Singleton.log != nil {
  		err = errors.New("You may not call Set after it has already been implicitly or explicitly set.")
  		_Singleton.log.Warning(err.Error())
  	} else {
  		_Singleton.log = logger
  	}
  	return
  }
docs: // Set configures the singleton Logger. This method
  // must only be called once, and before calling Get the
  // first time.