code: func (store *FileStore) Open() {
  	store.Lock()
  	defer store.Unlock()
  	// if no store directory was specified in ClientOpts, by default use the
  	// current working directory
  	if store.directory == "" {
  		store.directory, _ = os.Getwd()
  	}
  
  	// if store dir exists, great, otherwise, create it
  	if !exists(store.directory) {
  		perms := os.FileMode(0770)
  		merr := os.MkdirAll(store.directory, perms)
  		chkerr(merr)
  	}
  	store.opened = true
  	DEBUG.Println(STR, "store is opened at", store.directory)
  }
docs: // Open will allow the FileStore to be used.