issue with call for prev(TableName,ets:last(TableName),prev,EndBL)

https://github.com/CorticalComputer/Book_NeuroevolutionThroughErlang/blob/81b96e3d7985624a6183cb313a7f9bff0a7e14c5/Ch_19/fx.erl#L375

I have been trying for months to get this to work and still nothing any help would be greatly appreciated..... if anyone is even looking at this now..