title: How to return .xlsx file?
body: <p>how to return .xlsx file?<br><br>
  For example - when I'm going to "/download" - "File.xlsx" should start downloading.<br><br>
  I'm using bottle 0.12.7 and python 3.4
  I try to return it:</p>
  
  <pre><code>@route('/download')
  def download():
      return open('files/File.xlsx')
  </code></pre>
  
  <p>But Chrome returns me this error: <strong>ERR_EMPTY_RESPONSE</strong></p>
  
  <p>Thanks.</p>