drivers/google/compute_util.go
func (c *ComputeUtil) disk() (*raw.Disk, error) {
	return c.service.Disks.Get(c.project, c.zone, c.diskName()).Do()
}
func (c *ComputeUtil) disk() (*raw.Disk, error) {
	return c.service.Disks.Get(c.project, c.zone, c.diskName()).Do()
}
// disk returns the persistent disk attached to the vm.