code: func resourceVSphereDatastoreClusterVMAntiAffinityRuleFlattenID(pod *object.StoragePod, key int32) (string, error) {
  	podID := pod.Reference().Value
  	return strings.Join([]string{podID, strconv.Itoa(int(key))}, ":"), nil
  }
docs: // resourceVSphereDatastoreClusterVMAntiAffinityRuleFlattenID makes an ID for the
  // vsphere_datastore_cluster_vm_anti_affinity_rule resource.