echo
----
db0.Put(ctx, tk(1), sv(1)) // @0.000000001,0 <nil>
db0.Put(ctx, tk(1), sv(2)) // @0.000000002,0 <nil>
db0.Txn(ctx, func(ctx context.Context, txn *kv.Txn) error {
  txn.SetIsoLevel(isolation.Serializable)
  txn.Get(ctx, tk(1)) // (v1, <nil>)
  txn.Put(ctx, tk(2), sv(3)) // <nil>
  return nil
}) // @0.000000002,0 <nil>
/Table/100/"0000000000000001"/0.000000001,0 @ s1 v1
/Table/100/"0000000000000001"/0.000000002,0 @ s2 v2
/Table/100/"0000000000000002"/0.000000002,0 @ s3 v3
committed serializable txn non-atomic timestamps: [r]/Table/100/"0000000000000001":[0.000000001,0, 0.000000002,0)->v1 [w]/Table/100/"0000000000000002":0.000000002,0->v3@s3
