code: func createCircuitBreakerOptions(expression string) cbreaker.CircuitBreakerOption {
  	return cbreaker.Fallback(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
  		tracing.SetErrorWithEvent(req, "blocked by circuit-breaker (%q)", expression)
  		rw.WriteHeader(http.StatusServiceUnavailable)
  
  		if _, err := rw.Write([]byte(http.StatusText(http.StatusServiceUnavailable))); err != nil {
  			log.FromContext(req.Context()).Error(err)
  		}
  	}))
  }
docs: // NewCircuitBreakerOptions returns a new CircuitBreakerOption