static LS gazelle_answersFromModules(S userID, S input) {
  new LS out;
  LS modules = cast dm_call(dm_gazelle_modulesManager(), 'activeModulesForUser, userID);
  for (S moduleID : unnull(modules)) pcall {
    addIfNempty(out, (S) dm_callOpt(moduleID, 'answer, input));
  }
  ret out;
}