Depends who goes first.
If Black goes first, then it's either a seki or a ko which is White's privilege:
If White goes first, then it's dead:
This move makes it look like it's seki but it is not the case. If Black fills at either 'a' or 'b', then it dies. However, White can play at either 'a' or 'b' to threaten an eye inside, but Black can't save it or else it dies in a liberty shortage. I don't think
is even necessary, but it helps you see the shape better.edit: It's not dead! Black can play at 'c' and it becomes seki.
Black can't play at 'a' due to liberty shortage, but a White stone there only makes the dead shape (bulky 5) inside. (again,
is not necessary here either, but just to make it easier to see)If Black doesn't play inside and refuses to believe it is dead, you can show this shape (rabbity 6):
doesn't work because after 
below. B must answer 
.
