title: Observable `of` deprecated. What is the equivalent?
body: <p>In my case, I have an access token, and should that token exist, I would return it as an observable of type string:</p>
  
  <pre><code>if (this.accessToken){
    return of(this.accessToken);
  }
  </code></pre>
  
  <p>Due to a recent update, I noticed that <code>of</code> is deprecated with the following message:</p>
  
  <p><code>of is deprecated: use scheduled instead 'scheduled([a, b, c], scheduler)' (deprecation)</code></p>
  
  <p>The new syntax is quite verbose,  would anyone know the equivalent <code>scheduled</code> version of the same simple <code>of</code>?  The keyword name makes it difficult to search for information on it. </p>
  
  <p>Thanks!</p>