static S ai_makeVerbAction(S text, L<IntRange> r) {
  if (r == null) null;
  if (l(r) != 1) todo();
  int i = trimIndexRight(text, first(r).start);
  int j = trimIndexLeft(text, first(r).end);
  ret j <= i ? null : "verb=" + quote(substring(text, i, j)) + " (" + i + "/" + (j-i) + ")";
}