Answer the following questions to check what you've learned in this chapter:

1. In a SignalR hub class, what method can we use to push data to a group of connected clients?
2. In a SignalR hub class, what method can we use to push data to all clients except for the client that has made the request?
3. Why did we need a CORS policy for our React app to be able to interact with our SignalR real-time API?
4. In our React frontend, why did we check whether the connection was in a connected state before subscribing to the question? 
5. Why do we stop the connection when the user navigates away from the question page?