title: Wsgiref Error: AttributeError: 'NoneType' object has no attribute 'split'
body: <p>I am trying to implement my own version of wsgiref for learning purpose and I ended up here:</p>
  
  <pre><code>from wsgiref.simple_server import make_server
  
  class DemoApp():
      def __init__(self, environ, start_response):
          self.environ = environ
          self.start = start_response
  
      def __iter__(self, status):
          self.status = '200 OK'
          response_headers = [('Content-type','text/plain')]
          self.start(status, response_headers)
          return ["Hello World"]
  
  
  if __name__ == '__main__':
      httpd = make_server('', 1000, DemoApp)
      print("Serving on port 1000")
      httpd.serve_forever()
  </code></pre>
  
  <p>When I go to port 1000, I am getting the attribute error.</p>
  
  <pre><code>AttributeError: 'NoneType' object has no attribute 'split'
  </code></pre>
  
  <p>Where am I leaving mistakes?</p>
  
  <p>Stacktrace:</p>
  
  <pre><code>Serving on port 1000
  Traceback (most recent call last):
    File "C:\Python27\lib\wsgiref\handlers.py", line 86, in run
      self.finish_response()
    File "C:\Python27\lib\wsgiref\handlers.py", line 131, in finish_response
      self.close()
    File "C:\Python27\lib\wsgiref\simple_server.py", line 33, in close
      self.status.split(' ',1)[0], self.bytes_sent
  AttributeError: 'NoneType' object has no attribute 'split'
  127.0.0.1 - - [11/Jan/2014 12:40:09] "GET / HTTP/1.1" 500 59
  Traceback (most recent call last):
    File "C:\Python27\lib\SocketServer.py", line 295, in _handle_request_noblock
  ----------------------------------------
  Exception happened during processing of request from ('127.0.0.1', 54469)
      self.process_request(request, client_address)
    File "C:\Python27\lib\SocketServer.py", line 321, in process_request
      self.finish_request(request, client_address)
    File "C:\Python27\lib\SocketServer.py", line 334, in finish_request
      self.RequestHandlerClass(request, client_address, self)
    File "C:\Python27\lib\SocketServer.py", line 649, in __init__
      self.handle()
    File "C:\Python27\lib\wsgiref\simple_server.py", line 124, in handle
      handler.run(self.server.get_app())
    File "C:\Python27\lib\wsgiref\handlers.py", line 92, in run
      self.close()
    File "C:\Python27\lib\wsgiref\simple_server.py", line 33, in close
      self.status.split(' ',1)[0], self.bytes_sent
  AttributeError: 'NoneType' object has no attribute 'split'
  </code></pre>