code: func getCacheStatsHandler(w http.ResponseWriter, r *http.Request) {
  	target, err := json.Marshal(cache.Stats())
  	if err != nil {
  		w.WriteHeader(http.StatusInternalServerError)
  		log.Printf("cannot marshal cache stats. error: %s", err)
  		return
  	}
  	// since we're sending a struct, make it easy for consumers to interface.
  	w.Header().Set("Content-Type", "application/json; charset=utf-8")
  	w.Write(target)
  	return
  }
docs: // returns the cache's statistics.