static void ai_spec_whatIsTheLength(S s) {
  new Matches m;
  if (!swic(unquote(s), "how long is ", m)) ret;
  S postUnder = optQuote(s);
  S thing = m.get(0);
  print("ai_spec_whatIsTheLength thing: " + thing);
  
  // trigger required speculations
  
  post(postUnder, "possibly related to:", thing);
  ai_triggerSpeculationOn(thing);
  
  // harvest answer
  post(ai_forward(thing, "has length"), "answers", postUnder);
}