title: map reduce "ORDER BY" 2 columns
body: <p>Here is my SQL query, which lists the youngest and most talented dogs:</p>
  
  <pre><code>SELECT * FROM dog
  ORDER BY dog.age ASC, dog.kudus DESC
  </code></pre>
  
  <p>How can I convert this to a map/reduce?</p>
  
  <pre><code>// Map
  function (doc) {
    emit([doc.age, doc.kudus], doc);
  }
  // Reduce
  function (keys, values) {
    return ???
  }
  </code></pre>