code: func NewObjectStore(getObject GetObjectFunc, clock clock.Clock, getTTL GetObjectTTLFunc, ttl time.Duration) Store {
  	return &objectStore{
  		getObject:  getObject,
  		clock:      clock,
  		items:      make(map[objectKey]*objectStoreItem),
  		defaultTTL: ttl,
  		getTTL:     getTTL,
  	}
  }
docs: // NewObjectStore returns a new ttl-based instance of Store interface.