title: bad request error 400 while using python requests.post function
body: <p>I'm trying to make a simple post request via the requests library of Python and I get a bad request error (400) while my url is supposedly correct since I can use it to perform a get.
  I'm very new in REST requests, I read many tutorials and documentation but I guess there are still things I don't get so my error could be basic. Maybe a lack of understanding on the type of url I'm supposed to send via POST. Here my code :</p>
  
  <pre><code>import requests
  v_username = "username"
  v_password = "password"
  v_headers = {'content-type':'application/rdf+xml'}
  url = 'https://my.url'
  params = {'param': 'val_param'}
  payload = {'data': 'my_data'}
  r = requests.post(url, params = params, auth=(v_username, v_password), data=payload, headers=v_headers, verify=False)
  print r
  </code></pre>
  
  <p>I used the example of the requests documentation.</p>