title: What does filter(loaded =>!loaded) do?
body: <p>This is from <a href="https://kimsereyblog.blogspot.com/2017/08/easily-ensure-that-data-is-loaded-with.html" rel="nofollow noreferrer">this Article</a>. What does the <code>filter(loaded =&gt; !loaded)</code> do? I don't see that variable defined anywhere.</p>
  
  <p>I understand what the purpose of the method it, just not that particular line.</p>
  
  <pre><code>canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) {
  
      // 1
      const isLoaded$ = this.store.select(fromRoot.getUsers)
        .map(users =&gt; users.length &gt; 0);
  
      // 2
      isLoaded$
        .take(1)
        .filter(loaded =&gt; !loaded)  // here
        .map(() =&gt; new user.LoadAllAction())
        .subscribe(this.store);
  
      // 3
      return isLoaded$
        .take(1);
    }
  </code></pre>