code: func (e *CombinedEtcdClient) Snapshot(version *EtcdVersion, snapshotFile string) error {
  	if version.Major != 3 {
  		return fmt.Errorf("etcd 3.x required but got version '%s'", version)
  	}
  	return e.runEtcdctlCommand(version,
  		"--endpoints", e.endpoint(),
  		"snapshot", "save", snapshotFile,
  	)
  }
docs: // Snapshot captures a snapshot from a running etcd3 server and saves it to the given snapshotFile.
  // We cannot use etcd/clientv3 to make this call. It is implemented in the etcdctl client code.