What’s the best way to call `unique_consecutive()`

on certain dimension of a tensor, and pad the left-out with specified values?

For simplicity, we could use 2D tensor as an example:

```
input = tensor([[3, 3, 5, 5, 5],
[3, 3, 2, 2, 3]])
```

if specifying padding value -1, what i hope to get is:

```
output = tensor([[3, 5, -1, -1, -1],
[3, 2, 3, -1, -1]])
```

Also, to save memory, i’d prefer to do so in-place if possible.

Thanks!