...
#[derive(Clone)]
struct Store {
    questions: Arc<RwLock<HashMap<QuestionId, Question>>>,
    answers: Arc<RwLock<HashMap<AnswerId, Answer>>>,
}

impl Store {
    fn new() -> Self {
        Store {
            questions: Arc::new(RwLock::new(Self::init())),
            answers: Arc::new(RwLock::new(HashMap::new())),
        }
    }
    fn init() -> HashMap<String, Question> {
        let file = include_str!("../questions.json");
        serde_json::from_str(file).expect("can't read questions.json")
    }
}

...

async fn add_answer(
    store: Store,