Hello! I'm just getting started with implementing SuperTokens on my site and it's relatively simple, but I'm struggling with one thing right now: I want to show a button that says "Login/Register" if a user is not logged in or their profile picture if they are. I'm sure there's a quick and easy way to check if a user is logged in, but I can't seem to find it. If it matters, I'm using Node/Express and React.