static MultiMap<S, IAttractor> litAttractorsBySpace(O... params) {
  S space = MultiSpaceReasoning1.objectiveSpace;
  new MultiMap<S, IAttractor> mm;
  for unnull (O o : params)
    if (o cast S)
      space = o;
    else if (o != null)
      mm.put(space, o/IAttractor);
  ret mm;
}