code: func (g *Cloud) ListLocations(ctx context.Context) ([]*tpuapi.Location, error) {
  	mc := newTPUMetricContext("list_locations", "")
  	parent := getTPUProjectURL(g.projectID)
  	response, err := g.tpuService.projects.Locations.List(parent).Do()
  	if err != nil {
  		return nil, mc.Observe(err)
  	}
  	return response.Locations, mc.Observe(nil)
  }
docs: // ListLocations returns the zones where Cloud TPUs are available.