Where is the nat sample?

Once in a while, there is a https://github.com/Netronome/bpf-samples/blob/master/nat sample in this BPF sample repo.

```bash
$ ls nat
demo  Makefile  nat  nat_common.h  nat_kern.c  nat_kern.ll  nat_kern.o  nat_user.c  README.rst
```

Does it seem gone right now? Where can I find it?