I've been trying to write a wrapper around get_slice that supports paging semantics.

I can get it to page forwards - starting with Start="" and then successively passing in a new Start / Count.

But when i try going backwards from the end, passing Start = "" and Finish = "X", it doesn't give me the N columns up to column X as I would expect.
It actually gives me a range of columns that fall much earlier in the paged set.

Any suggestions on where I might be going wrong ?