static L<S> paragraphsFromText(S text) {
  L<S> lines = toLinesTrim2(text);
  L<L<S>> paragraphs = paragraphsFromText_groupParagraphs(lines);
  ret map(paragraphs, func(L<S> p) { fromLines(p) });
}

static L<L<S>> paragraphsFromText_groupParagraphs(L<S> lines) {
  ret groupNonEmpty(lines, func(S line) { empty(line) });
}