title: Check whether email is subscribed to list in MailChimp API 3.0 using PHP
body: <p>I've just read the following on the MailChimp website:</p>
  
  <blockquote>
    <p>MailChimp API v3.0 is now live!
    Prior versions will no longer be supported after 2016, so all API users should begin transitioning to v3.0.</p>
  </blockquote>
  
  <p>As a result, I would like to move to v3.0 of the API. Please could I have a function, in PHP, that returns a boolean, that will check whether an email address is subscribed to a specific MailChimp list. I do not want to subscribe that user, but merely check whether they are subscribed or not.</p>