async fn auth_check<Fetch, Fut, Pdu>( rules: &RoomVersionRules, state: StateMap<OwnedEventId>, event_id: &EventId, state_key: StateKey, event: Pdu, fetch: &Fetch, ) -> Result<StateMap<OwnedEventId>>where Fetch: Fn(OwnedEventId) -> Fut + Sync, Fut: Future<Output = Result<Pdu>> + Send, Pdu: Event,