plus

Store 实例的创建并不要求一次性创建，你可以创建多个Store实例，然后使用这个扩展操作符进行组合。

Store instances don't need to be created all at once, you can create multiple Store instances and then use this extension operator Store.plus to combine

// provide store for all components
ReduxProvider(store = simpleStore + fetchStore) {
     // sub components
}