title: Multiple CTE in single query
body: <p>Is it possible to combine multiple CTEs in single query with <code>arel</code>? I am looking for way to get result like this:</p>
  <pre><code>WITH cte1 AS (
  ...
  ),
  WITH RECURSIVE cte2 AS (
  ...
  ),
  WITH cte3 AS (
  ...
  )
  SELECT ... FROM cte3 WHERE ...
  </code></pre>
  <p>As you can see, I have one recursive CTE and two non recursive.</p>