title: Find latest date of document based on 2 separate fields: month and year
body: <p>I have documents in mongoDB that look like this:</p>
  
  <pre><code>{username:String, paymentYear:Int, paymentMonth:Int}
  </code></pre>
  
  <p>I would like to find the latest document of a username, that means, the closest date to our Date.now(). What is the best way of accomplishing it? Is there any query of mongo I can use or should I write my own code?</p>
  
  <p>Thanks</p>