title: How do you utilize $and, $or, $exists in the same Mongoose.js query?
body: <p>I need to query documents for an account that either has no expiration[expires] (does not exist) or the expiration date is after 2/2/14.  To do so, my mongodb query is:</p>
  
  <pre><code>db.events.find({ _account: ObjectId("XXXX"), 
      $or: [
          {expires: {$gt: ISODate('2014-02-02')}}, 
          {expires: {$exists: false}}
      ]
  });
  </code></pre>
  
  <p>I'm having trouble with the correct mongoose <code>.or()</code> <code>.and()</code> <code>.exists()</code> chaining, how would I convert this into Mongoose?</p>
  
  <p>Thanks!</p>