title: How to subscribe to multiple channels on Redis NodeJS
body: <p>I have a function which I will call from time to time.</p>
  
  <pre><code>function blah() {
     sub.unsubscribe();
     sub.subscribe("a");
     sub.subscribe("b");
  }
  </code></pre>
  
  <p>Above results in error message "Error: node_redis command queue state error."</p>