smichr/sympy — comment on commit 29036dd7008b48969dd2b729fcd14bd10296ace5
File: sympy/combinatorics/subsets.py line 371
By smichr:

On Wed, Nov 23, 2011 at 6:11 PM, Saptarshi Mandal

wrote:
> You could write a doctest that shows the case when you croak.

Do you mean one where the subset is not actually a subset?

>
> I like this routine, not only is it quite clever, it also does takes corner cases into account as well. However, I think trying to create a subset whose elements are not in its superset will raise an error in the constructor itself.

Perhaps...I thought I recalled seeing a case where the indices were []
and that's what clued me in to return []...Maybe that's for a null
subset.