htc_3_19.swift

func transform(
    newsReducer: @escaping (NewsState, AppEvent) -> NewsState,
    appStateIntoNews: @escaping (AppState) -> NewsState,
    mutateAppStateWithNewsState: @escaping (AppState, NewsState) -> AppState
) -> Reducer {
    return { appState, appEvent in
        let newsState = appStateIntoNews(appState)
        let newNewsState = newsReducer(newsState, appEvent)
        return mutateAppStateWithNewsState(appState, newNewsState)
    }
}