static S ai_textOfChatLine(S line) {
  if (!swicOneOf(line, "chat line ", "Smart Bot's Chat line ")) null;
  S a = firstQuoted(ai_texts_verified(line, "has text", "$X"));
  if (a != null) ret unquote(a);
  ret unquote(firstQuoted(ai_texts_verified(line, "has text", "$X")));
}