code: public static ModelMetrics getFromDKV(Key key) {
      if (null == key)
        throw new IllegalArgumentException("Got null key.");
  
      Value v = DKV.get(key);
      if (null == v)
        throw new IllegalArgumentException("Did not find key: " + key.toString());
  
      Iced ice = v.get();
      if (! (ice instanceof ModelMetrics))
        throw new IllegalArgumentException("Expected a Model for key: " + key.toString() + "; got a: " + ice.getClass());
  
      return (ModelMetrics)ice;
    }
docs: TODO: almost identical to ModelsHandler; refactor