code: func NewWorkerOpt(root string, address, snapshotterName, ns string, labels map[string]string, opts ...containerd.ClientOpt) (base.WorkerOpt, error) {
  	opts = append(opts, containerd.WithDefaultNamespace(ns))
  	client, err := containerd.New(address, opts...)
  	if err != nil {
  		return base.WorkerOpt{}, errors.Wrapf(err, "failed to connect client to %q . make sure containerd is running", address)
  	}
  	return newContainerd(root, client, snapshotterName, ns, labels)
  }
docs: // NewWorkerOpt creates a WorkerOpt.