code: func (v *Cloud) InstanceID(ctx context.Context, nodeName types.NodeName) (string, error) {
  	name := mapNodeNameToInstanceName(nodeName)
  	instance, err := v.fetchInstance(name)
  	if err != nil {
  		return "", err
  	}
  	// TODO: define a way to identify the provider instance to complete
  	// the format <provider_instance_id>/<instance_id>.
  	return "/" + instance.UUID, err
  }
docs: // InstanceID returns the cloud provider ID of the node with the specified NodeName.