code: func NewObjectCache(f func() (interface{}, error), ttl time.Duration) *ObjectCache {
  	return &ObjectCache{
  		updater: f,
  		cache:   expirationcache.NewTTLStore(stringKeyFunc, ttl),
  	}
  }
docs: // NewObjectCache creates ObjectCache with an updater.
  // updater returns an object to cache.