code: func (manager *impl) ListCheckpoints() ([]string, error) {
  	manager.mutex.Lock()
  	defer manager.mutex.Unlock()
  	keys, err := manager.store.List()
  	if err != nil {
  		return []string{}, fmt.Errorf("failed to list checkpoint store: %v", err)
  	}
  	return keys, nil
  }
docs: // ListCheckpoints returns the list of existing checkpoints.