code: func NewCheckpointManager(checkpointDir string) (CheckpointManager, error) {
  	fstore, err := utilstore.NewFileStore(checkpointDir, utilfs.DefaultFs{})
  	if err != nil {
  		return nil, err
  	}
  
  	return &impl{path: checkpointDir, store: fstore}, nil
  }
docs: // NewCheckpointManager returns a new instance of a checkpoint manager