Presumable not just this shallow case, but OrderBy and Skip should have relation for fast operation. Test [here](https://github.com/manofstick/Cistern.Linq/blob/master/src/Cistern.Linq.Tests/OrderedSubsetting.cs#L228-L233). Another example in the tests [is here](https://github.com/manofstick/Cistern.Linq/blob/master/src/Cistern.Linq.Tests/TakeTests.cs#L463-L473).
