code: func NewSchemaSyncer(etcdCli *clientv3.Client, id string) SchemaSyncer {
  	return &schemaVersionSyncer{
  		etcdCli:           etcdCli,
  		selfSchemaVerPath: fmt.Sprintf("%s/%s", DDLAllSchemaVersions, id),
  	}
  }
docs: // NewSchemaSyncer creates a new SchemaSyncer.