title: Predicate to retrieve a user's followers
body: <p>Say I have the relationship </p>
  
  <p><strong>Followers / Following</strong><br>
  <code>User &lt;&lt;---&gt;&gt; User</code></p>
  
  <p>As a result, UserA.following = [UserB] means UserB.followers = [UserA].</p>
  
  <p>I'm watching changes through <code>NSFetchedResultsController</code> and need a predicate to simply pull the 1:Many relationship. If this was code, it'd be pretty easy, I would just say <code>user.followers</code>, but since the fetch controller needs a predicate, I'm stumbling up on how to express the query. </p>