struct AppState<'a> {
    services: &'a AppServices<'a>,
}

impl<'a> AppState<'a> {
    pub fn new() -> Self {
        AppState {
            services: &AppServices { id: None },
        }
    }
}

struct AppServices<'a> {
    id: Option<&'a IdService<'a>>,
}

struct IdService<'a> {
    name: String,
    state: &'a AppState<'a>,
}