title: Python Flask, how to set content type
body: <p>I am using Flask and I return an XML file from a get request. How do I set the content type to xml ?</p>
  
  <p>e.g.</p>
  
  <pre><code>@app.route('/ajax_ddl')
  def ajax_ddl():
      xml = 'foo'
      header("Content-type: text/xml")
      return xml
  </code></pre>