code: func (client *Client) redactError(err error) error {
  	if err == nil {
  		return nil
  	}
  	errString := err.Error()
  
  	if len(client.apiKey) > 0 {
  		errString = strings.Replace(errString, client.apiKey, "redacted", -1)
  	}
  	if len(client.appKey) > 0 {
  		errString = strings.Replace(errString, client.appKey, "redacted", -1)
  	}
  
  	// Return original error if no replacements were made to keep the original,
  	// probably more useful error type information.
  	if errString == err.Error() {
  		return err
  	}
  	return fmt.Errorf("%s", errString)
  }
docs: // redactError removes api and application keys from error strings