code: func volumeExists(ctx context.Context, store *drivers.Store, v volume.Volume) (bool, error) {
  	exists, err := lookupVolume(ctx, store, v.DriverName(), v.Name())
  	if err != nil {
  		return false, err
  	}
  	return exists != nil, nil
  }
docs: // volumeExists returns if the volume is still present in the driver.
  // An error is returned if there was an issue communicating with the driver.