title: How do I check if an observable is running and stop it?
body: <p>So I have an observable with a debounce of 300ms.<br>
  It does an API-call after a key-up event.</p>
  
  <p>There's an API-lock in place to prevent future calls until it is completed, but I would also like to check if the observable is running (that's making the API call) and stop it.</p>
  
  <p>How would this be accomplished?</p>