code: func (e *elasticError) Error() string {
  	if e.Details != nil && e.Details.Reason != "" {
  		return fmt.Sprintf("elastic: Error %d (%s): %s [type=%s]", e.Status, http.StatusText(e.Status), e.Details.Reason, e.Details.Type)
  	}
  	return fmt.Sprintf("elastic: Error %d (%s)", e.Status, http.StatusText(e.Status))
  }
docs: // Error returns a string representation of the error.