code: func (a *flexVolumeAttacher) Attach(spec *volume.Spec, hostName types.NodeName) (string, error) {
  
  	call := a.plugin.NewDriverCall(attachCmd)
  	call.AppendSpec(spec, a.plugin.host, nil)
  	call.Append(string(hostName))
  
  	status, err := call.Run()
  	if isCmdNotSupportedErr(err) {
  		return (*attacherDefaults)(a).Attach(spec, hostName)
  	} else if err != nil {
  		return "", err
  	}
  	return status.DevicePath, err
  }
docs: // Attach is part of the volume.Attacher interface