[Noughty]

I tried the
{tags:'list_sort(list_union('', re(subitems($, 0, 0), '(^|,)([^,]*?)\.', '\1 '), ','), '0', ',')'}

This works best if tags are two level, like Genre.Mystery, But if it is something like Character.Profession.Law enforcement it gives me Profession.Law enforcement and I would like to get only the last tag no matter how many levels there are.
How to edit it so it does that?
Here's the expected result:
Mystery>Mystery
Genre.Mystery>Mystery
Character.Profession.Law enforcement>Law enforcement
Book.Type.Anthology>Anthology

So if a book had these tags I would see final result as:
Anthology, Law enforcement, Mystery

I'm not sure I want to sort as it will give tags in category order, first all about the book, when character, when genre and so on. So I think it's better that sorting alphabetically. I removed sorting function but it still gives result sorted:
{#shelf:'list_union('', re(subitems($, 2, 4), '(^|,)([^,]*?)\.', '\1 '), ',')'}