code: func (r *DiskSubresource) findVirtualDisk(l object.VirtualDeviceList, fallback bool) (*types.VirtualDisk, error) {
  	device, err := r.findVirtualDiskByUUIDOrAddress(l, fallback)
  	if err != nil {
  		return nil, err
  	}
  	return device.(*types.VirtualDisk), nil
  }
docs: // findVirtualDisk locates a virtual disk by it UUID, or by its device address
  // if UUID is missing.
  //
  // The device address search is only used if fallback is true - this is so that
  // we can distinguish situations where it should be used, such as a read,
  // versus situations where it should never be used, such as an update or
  // delete.