code: func migrate(name string, port uint64, peerListenUrls string, peerAdvertiseUrls string, binPath string, dataDirPath string, etcdDataPrefix string, ttlKeysDirectory string,
  	initialCluster string, target *EtcdVersionPair, bundledVersions SupportedVersions, etcdServerArgs string) {
  
  	dataDir, err := OpenOrCreateDataDirectory(dataDirPath)
  	if err != nil {
  		klog.Errorf("Error opening or creating data directory %s: %v", dataDirPath, err)
  		os.Exit(1)
  	}
  
  	cfg := &EtcdMigrateCfg{
  		binPath:           binPath,
  		name:              name,
  		port:              port,
  		peerListenUrls:    peerListenUrls,
  		peerAdvertiseUrls: peerAdvertiseUrls,
  		etcdDataPrefix:    etcdDataPrefix,
  		ttlKeysDirectory:  ttlKeysDirectory,
  		initialCluster:    initialCluster,
  		supportedVersions: bundledVersions,
  		dataDirectory:     dataDirPath,
  		etcdServerArgs:    etcdServerArgs,
  	}
  	client, err := NewEtcdMigrateClient(cfg)
  	if err != nil {
  		klog.Errorf("Migration failed: %v", err)
  		os.Exit(1)
  	}
  	defer client.Close()
  
  	migrator := &Migrator{cfg, dataDir, client}
  
  	err = migrator.MigrateIfNeeded(target)
  	if err != nil {
  		klog.Errorf("Migration failed: %v", err)
  		os.Exit(1)
  	}
  }
docs: // migrate opens or initializes the etcd data directory, configures the migrator, and starts the migration.