code: func NewTTLStore(keyFunc KeyFunc, ttl time.Duration) Store {
  	return &ExpirationCache{
  		cacheStorage:     NewThreadSafeStore(Indexers{}, Indices{}),
  		keyFunc:          keyFunc,
  		clock:            util.RealClock{},
  		expirationPolicy: &TTLPolicy{ttl, util.RealClock{}},
  	}
  }
docs: // NewTTLStore creates and returns a ExpirationCache with a TTLPolicy