title: wants to get http request from python requests module
body: <p>I wants to use python requests module to prepare http request and use http socket to send the request, So I can detect the connection problem.
  Can anyone suggest how should I retrieve raw request from python requests module(without sending request)</p>
  
  <pre><code>from requests import Request, Session
  for m in ['GET', 'POST']:
      s = Session()
      req = Request(m, url,
          data=data,
          headers=header
      )
      prepped = req.prepare()
      # how to retrieve raw request from prepped 
  </code></pre>