Pytorch, get the index of the first 0 in as mask?

I have a tensor that looks like: (1, 1, 1, 1, 1, 1, 1, 1, 0, 0).
I want to get the index where the first zero appears.
What would the be best way do this?

>Solution :

Not the best usage of argmin but it should work here I think:

>>> torch.tensor([1, 1, 1, 1, 1, 1, 1, 1, 0, 0]).argmin()
tensor(8)