so, original request ( https://news.ycombinator.com/item?id=33014879 ) was for iterator highlighter ( rollup / non-rollup)
1) neo-minimap : https://www.reddit.com/r/neovim/comments/y2ubty/neominimap_create_your_own_minimap_from/
need knowledge of treesitter query syntax & types of iterators of programming language of interest.
regular expression extension a future extension.