@awilliams gave a great illustration to get the elements. Your link dates back to 2014 (has it been that long?). As @Andreas_Dieckmann mentioned those nodes were replaced by out of the box (OOTB) nodes and as a result you should use those. To get your desired output you can try the following.
- Use a List.Transpose node to reorganize the data from the Element.GetParameterValueByName node.
- Use a List.FirstItem node and a List.LastItem node to separate the list into separate lists.
- Use a String.Join node where the first input is the sheet numbers, the second list is the sheet names, and the separator is a string value of " - ".
If you struggle with replicating @awilliams’ solution or working out the directions above I suggest you visit the Dynamo primer and do every exercise, the ones which are confusing twice. Don’t skip any even if they feel like you don’t need them - the content there is curated to let you know the concepts required to understand how to work through these sort of problems, and that understanding will save you time in the long run.