Proposal: allow tuples instead of slice objects in sel or isel

[shoyer]

e.g., we should be able to write ds.sel(time=('2000', '2010')) as an alias for ds.sel(time=slice('2000', '2010'))

[shoyer]

Two concerns occur to me about this change:

1. It does break backward compatibility.
2. It currently possible to use an index of tuples (and eventually, we'll support multi-index), and this would break that.

[IamJeffG]

I agree with your concerns and vote "-1" on this proposal.

When I read ds.sel(time=('2000', '2010')) with no outside context, I expect to get back exactly two ticks along the time axis: that equal to '2000' and that equal to '2010'. (reminiscent of #214, though multidimensional is trickier)

[shoyer]

OK, closing.

The real fix here will require new Python syntax to support ds[time='2000':'2010']