HELP: How to implement Nested/Hierarchy Checklist?

Dear Experts,

I was looking for interactive checklist and found very good example at this link.

I have attached one of the example file taken from there.
checklist.PNG

I was wondering if it's possible to create a nested list/hierarchy based on this attached example i.e. Topic.Subtopic.subsubtopic.item, ( list goes up to five levels deep e.g. 2.1.5.3.1 ) ? In the attached example when user clicks on Topic the items related to this topic Collapse/hide.

The author commented to one of the user there as

The current implementation simply differentiates between topics and items using two Boolean functions (IsItem and IsTopic). The functions check whether there is a separator (a period) in the first column of the list and if there is one, it is an item, otherwise it is a topic.
not only check if there is a separator, but rather count the separators to decide which level has been checked.

someone please help me !!!!, I have no VBA experience, unfortunately.