public void addProduct(Product prod){ 
    if(!products.contains(prod)){
      products.add(prod);
    }
    
    String family = unifyString(prod.get_family()).replaceAll(" ", "");
    String model =  unifyString(prod.get_model());
            
    if(!family_models_map.containsKey(family)){
      HashMap<String,Integer> model_map  = new HashMap();
      family_models_map.put(family,model_map);
    }

    HashMap models_id_map = family_models_map.get(family);
    models_id_map.put(model,new Integer(next_id)); 
    next_id++;   
  }