static LPair<GazelleLine> gazelle_allPossibleAnswersGivenToHumans(O... _) {
  int maxDelay = optPar maxDelay(_, 10000); // between question and answer
  new LPair<GazelleLine> out;
  for (long channelID : dm_discord_allChannelIDs()) {
    L<GazelleLine> l = dm_discord_linesInChannel(channelID);
    for (Pair<GazelleLine> p : overlappingPairs(l)) {
      continue unless !p.a.bot && p.b.bot;
      continue unless p.b.timestamp <= p.a.timestamp+maxDelay;
      out.add(p);
    }
  }
  ret out;
}