echo
----
db0.Txn(ctx, func(ctx context.Context, txn *kv.Txn) error {
  txn.SetIsoLevel(isolation.Serializable)
  txn.Put(ctx, tk(1), sv(1)) // <nil>
  txn.CreateSavepoint(ctx, 2) // <nil>
  return nil
}) // @0.000000001,0 <nil>
/Table/100/"0000000000000001"/0.000000001,0 @ s1 v1
