[TutorialsPython] TRIQS/unstable - magic %%triqs -u stl

In the notebook TRIQSTutorialsPython/other/trace.ipynb
the triqs-magic is used with the ```-u stl``` option that does not seem to exist anymore

```
UsageError: unrecognized arguments: -u stl
```

What does this do and how should this be adjusted for TRIQS/unstable?