code: func (g *Cloud) findDiskByName(diskName string, zone string) (*Disk, error) {
  	mc := newDiskMetricContextZonal("get", g.region, zone)
  	disk, err := g.manager.GetDiskFromCloudProvider(zone, diskName)
  	if err == nil {
  		return disk, mc.Observe(nil)
  	}
  	if !isHTTPErrorCode(err, http.StatusNotFound) {
  		return nil, mc.Observe(err)
  	}
  	return nil, mc.Observe(nil)
  }
docs: // Returns a Disk for the disk, if it is found in the specified zone.
  // If not found, returns (nil, nil)