title: should I use .rank or .order_id?
body: <p>accessing <code>order_id</code> property of a <code>ScoredDocument</code> object in <code>SearchResults</code> object generates following error in log:</p>
  
  <p><code>DeprecationWarning: order_id is deprecated; use rank instead
    logging.debug(document.order_id)</code></p>
  
  <p>However documentation here refers to <code>order_id</code>: <a href="https://developers.google.com/appengine/docs/python/search/scoreddocumentclass" rel="nofollow">https://developers.google.com/appengine/docs/python/search/scoreddocumentclass</a></p>
  
  <p>Which is correct? I am using SDK 1.7.3.</p>