How can I use gridspec?

Could anyone show me how to use gridspec?
```jl
fig = figure();
gs = fig.add_gridspec(2,2);
ax1 = fig.add_subplot(gs[0,0]); # this works
ax2 = fig.add_subplot(gs[1,0:1]); #This does not work
```
I get the following error:
```jl
ERROR: Python: TypeError: '<' not supported between instances of 'range' and 'int'
```

Start by reproducing the shown `fig.add_gridspec` and `fig.add_subplot` calls, especially the `gs[1,0:1]` expression, and inspect how these entry points handle Julia indexing before the Python call. Done means determining whether the usage is supported and documenting or correcting the behavior with a regression test.

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