title: Twilio TaskRouter: How to match worker based on activity
body: <p>In a routing step I would like to only match a task to a worker if that worker is in a specific activity; I've created a custom activity called 'outbound'. I've tried the following in the expressions </p>
  
  <pre><code>worker.activity == "outbound" 
  </code></pre>
  
  <p>and </p>
  
  <pre><code>worker.activity_name == "outbound"
  </code></pre>
  
  <p>both of these did not work; is this possible to do</p>