code: func checkRbdNbdTools(e mount.Exec) bool {
  	_, err := e.Run("modprobe", "nbd")
  	if err != nil {
  		klog.V(5).Infof("rbd-nbd: nbd modprobe failed with error %v", err)
  		return false
  	}
  	if _, err := e.Run("rbd-nbd", "--version"); err != nil {
  		klog.V(5).Infof("rbd-nbd: getting rbd-nbd version failed with error %v", err)
  		return false
  	}
  	klog.V(3).Infof("rbd-nbd tools were found.")
  	return true
  }
docs: // Check if rbd-nbd tools are installed.