code: private Pair<Map<String, Model>, Map<String, Set<String>>> fetchModels() {
      Map<String, Model> all_models = null;
      Map<String, Set<String>> all_models_cols = null;
  
      if (this.find_compatible_models) {
        // caches for this request
        all_models = (new Models()).fetchAll();
        all_models_cols = new TreeMap<String, Set<String>>();
  
        for (Map.Entry<String, Model> entry : all_models.entrySet()) {
          all_models_cols.put(entry.getKey(), new TreeSet<String>(Arrays.asList(entry.getValue()._names)));
        }
      }
      return new Pair<Map<String, Model>, Map<String, Set<String>>>(all_models, all_models_cols);
    }
docs: Fetch all the Models so we can see if they are compatible with our Frame(s).