code: func (u *RBDUtil) rbdStatus(image string, pOpts *rbdProvisionOptions) (bool, error) {
  	var err error
  	var output string
  	var cmd []byte
  
  	mon := u.kernelRBDMonitorsOpt(pOpts.monitors)
  	// cmd "rbd status" list the rbd client watch with the following output:
  	//
  	// # there is a watcher (exit=0)
  	// Watchers:
  	//   watcher=10.16.153.105:0/710245699 client.14163 cookie=1
  	//
  	// # there is no watcher (exit=0)
  	// Watchers: none
  	//
  	// Otherwise, exit is non-zero, for example:
  	//
  	// # image does not exist (exit=2)
  	// rbd: error opening image kubernetes-dynamic-pvc-<UUID>: (2) No such file or directory
  	//
  	klog.V(4).Infof("rbd: status %s using mon %s, pool %s id %s key %s", image, mon, pOpts.pool, pOpts.adminID, pOpts.adminSecret)
  	args := []string{"status", image, "--pool", pOpts.pool, "-m", mon, "--id", pOpts.adminID, "--key=" + pOpts.adminSecret}
  	cmd, err = u.execCommand("rbd", args)
  	output = string(cmd)
  
  	// If command never succeed, returns its last error.
  	if err != nil {
  		return false, err
  	}
  
  	if strings.Contains(output, imageWatcherStr) {
  		klog.V(4).Infof("rbd: watchers on %s: %s", image, output)
  		return true, nil
  	}
  	klog.Warningf("rbd: no watchers on %s", image)
  	return false, nil
  }
docs: // rbdStatus checks if there is watcher on the image.
  // It returns true if there is a watcher onthe image, otherwise returns false.