Should be equivalent, but the former is more likely to be supported than
the latter according to some docs that I read that I can no longer find.
" Returns an underlined copy of `group` suitable for passing to `:highlight`.
function! pinnacle#underline(group) abort
- return pinnacle#decorate('undercurl', a:group)
+ return pinnacle#decorate('underline', a:group)
endfunction
" Returns a copy of `group` decorated with `style` (eg. "bold", "italic" etc)