code: func (g *Cloud) ListClusters(ctx context.Context) ([]string, error) {
  	allClusters := []string{}
  
  	for _, zone := range g.managedZones {
  		clusters, err := g.listClustersInZone(zone)
  		if err != nil {
  			return nil, err
  		}
  		// TODO: Scoping?  Do we need to qualify the cluster name?
  		allClusters = append(allClusters, clusters...)
  	}
  
  	return allClusters, nil
  }
docs: // ListClusters will return a list of cluster names for the associated project