code: func (expBackoff *ExponentialBackoff) SafeToRetry(operationName string) error {
  	if time.Since(expBackoff.lastErrorTime) <= expBackoff.durationBeforeRetry {
  		return NewExponentialBackoffError(operationName, *expBackoff)
  	}
  
  	return nil
  }
docs: // SafeToRetry returns an error if the durationBeforeRetry period for the given
  // lastErrorTime has not yet expired. Otherwise it returns nil.