function Sep()
    if &commentstring =~ "%s"
        let tw = &textwidth > 0 ? &textwidth : 79
        let cs = substitute(substitute(&commentstring, '%s\zs\s*\ze\S', "|", ""), '\S\zs\s*\ze%s', "|", "")
        " let sf = substitute(substitute(&commentstring, '%s\zs\s*\ze\S', "|", ""), '.*%s', "", "")
        " let pf = substitute(substitute(&commentstring, '\S\zs\s*\ze%s', "|", ""), '%s.*', "", "")
        let rn = range(stridx(cs, "%s"), tw - strlen(cs) + 3)
        let md = join(map(rn, {key, val -> val % 8 == 0 ? "^" : "-"}), "")
        call append(line(".") - 1, substitute(cs, "%s", md, ""))
    else
        echoerr "Comment string is not defined in this buffer."
    endif
endfunction

command Sep :call Sep()