title: HTTP Error 409: conflict urllib2 python
body: <p>I would like to iterate over a list of url api requests with different ?get variables (x1,....,xn). </p>
  
  <pre><code>from urllib2 import urlopen, Request
  import pandas as pd
  
  var=[x[0],...,x[n]]
  url_list=['http://BLAH/get?var[0]&amp;fmt=csv','http://BLAH/get?var[1]&amp;fmt=csv',...      ...,'http://BLAH/get?var[n]&amp;fmt=csv']
  
  j=0
  while j &lt; len(url_list):
      req=Request(url_list[j])
      response=urlopen(req)
      df=pd.read_csv(response)
      print df
      j=j+1**
  </code></pre>
  
  <p>I have tried to del req and response.close() but my code still produces a conflict error.</p>
  
  <pre><code> File "C:\Users\Anaconda\lib\urllib2.py", line 127, in urlopen
    return _opener.open(url, data, timeout)
   File "C:\Users\Anaconda\lib\urllib2.py", line 410, in open
    response = meth(req, response)
   File "C:\Users\Anaconda\lib\urllib2.py", line 523, in http_response
    'http', request, response, code, msg, hdrs)
   File "C:\Users\nfitzsimons\Anaconda\lib\urllib2.py", line 448, in error
     return self._call_chain(*args)
   File "C:\Users\Anaconda\lib\urllib2.py", line 382, in _call_chain
     result = func(*args)
   File "C:\Users\Anaconda\lib\urllib2.py", line 531, in http_error_default
     raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
      rllib2.HTTPError: HTTP Error 409: Conflict
  </code></pre>
  
  <p>Has anybody any suggestions?</p>