title: Is there any functions to check topic subscription or un-subscription status in Firebase Cloud Messaging?
body: <p>In my settings screen, I provide users notifications switchers each topics. So I would like to make sure with the status when I subscribe or unsubscribe to turn-on or turn-off the switchers UI. Actually I found where can I get topics subscribed each users from this URL <a href="https://developers.google.com/instance-id/reference/server" rel="noreferrer">https://developers.google.com/instance-id/reference/server</a>.</p>
  
  <p>Is there any easier way to check them? (e.g. Get information about app)</p>
  
  <p><img src="https://i.stack.imgur.com/hQtY5.png" alt="e.g. Get information about app"></p>