code: func RateLimited(detail string, a ...interface{}) *ProblemDetails {
  	return &ProblemDetails{
  		Type:       RateLimitedProblem,
  		Detail:     fmt.Sprintf(detail, a...),
  		HTTPStatus: statusTooManyRequests,
  	}
  }
docs: // RateLimited returns a ProblemDetails representing a RateLimitedProblem error