static L<PairS> minusSignSectionPairs(S text) {
  LS lines = lines(text);
  L<Int> l = indicesOfStartingWithTrim(lines, "--");
  new L<PairS> out;
  
  // prelude
  if (nempty(l)) {
    S s = rtrim(lines(subList(lines, 0, first(l))));
    if (nempty(s))
      addPair(out, "", s);
  }
  
  for i over l: {
    int i1 = l.get(i);
    int i2 = or(get(l, i+1), l(lines));
    S heading = trim(lines.get(i1));
    int iHeading = 0;
    while (iHeading < l(heading) && heading.charAt(iHeading) == '-') iHeading++;
    heading = trim(substring(heading, iHeading));
    addPair(out, heading, lines(subList(lines, i1+1, i2)));
  }
  ret out;
}