Actix future resolve with wait(ctx). Get result to calling scope

Question

I extended the Actix web socket chat example a little bit. The chat rooms are Actors so thy can run some independent logic like a game.

In one Actor I have a handler for the message "Join". Inside this handler I want to send a message to another actor and wait for the response. How is this possible?

I use the addr.send().into_actor(self).then(...).wait(ctx) pattern. But this doesent return anything else then ().

fn handle(&mut self, msg: Join, ctx: &mut Self::Context) -> Self::Result {
        let Join {
            session_id,
            room_name,
            old_room_addr,
        } = msg;

        // remove address from room and add to the new one.
        let session_addr = match self.sessions.get(&session_id) {
            Some(res) => res,
            None => panic!("Session id is not in the chat server. This should not happend."),
        };


        old_room_addr
            .send(RemoveSession(session_id))
            .into_actor(self)
            .then(|res, _act, _ctx|{
                match res {
                    Ok(res) => {
                        if !res {
                            panic!("The session_id is not inside the room.");
                        }
                    },
                    Err(err) => panic!("Mailbox error while trying to remove the session from the room. {}", err),
                }
                fut::ready(())
            })
            .wait(ctx);

What I want is something like:

let result = old_room_addr.send(...).into_actor(...).then(...).wait(...);