Generate negative indices from the slices() strategy

[Zac-HD]

For example, slices(size=3) should be able to generate slice(-3, -1) as an equivalent form of slice(0, 2). We should also sometimes draw step=None if step=1 would be allowed. It would also be nice to support slicing length-zero sequences, i.e. if size == 0: return builds(slice, none(), none(), none() | integers().filter(bool)).

Both would be helpful for downstream users - see e.g. Quansight-Labs/ndindex#46.

[kir0ul]

Oh damn, was working on that one too 🙁

[Zac-HD]

Sorry @kir0ul 😕