docs: private Relation<ParameterizationFunction> preprocess(Relation<V> vrel) {
      DBIDs ids = vrel.getDBIDs();
      SimpleTypeInformation<ParameterizationFunction> type = new SimpleTypeInformation<>(ParameterizationFunction.class);
      WritableDataStore<ParameterizationFunction> prep = DataStoreUtil.makeStorage(ids, DataStoreFactory.HINT_HOT, ParameterizationFunction.class);
  
      // Project
      for(DBIDIter iter = ids.iter(); iter.valid(); iter.advance()) {
        prep.put(iter, new ParameterizationFunction(vrel.get(iter)));
      }
      return new MaterializedRelation<>(type, ids, null, prep);
    }