How do I find *only* the first occurrence of an element in each row of a 2D tensor?

For instance, if the input is:

```
t = torch.Tensor([[10, 1, 2, 3, 4, -10, -10,-10],
[10, 4, 2, 3, -10, -10, -10, -10],
[10, 1, 2, 3, 4, 5, 6, -10]])
```

And I wish to find the first occurrence of `value=-10`

in every row of the tensor. Therefore, I would like the output to be:

`tensor([5, 4, 7])`

How would I go about this without using for loops and using torch-native operations?