Anyway, I thought the only thing list_re_group() did was to apply templates and stuff to replacements in a list -- I just realized you can limit what gets passed to the re_group with a separator AND a regex.
P.S. The documentation for all three functions you added is a little weird, indented plus list_re_group is referred to as list_re (the second one???) in template_ref.html
The indents I believe are because the documentation builder does hierarchical bulleted lists when it sees tabs. You indented with tabs, which is usually
reasonable. All of Kovid's functions are indented with four spaces.