code: def request_and_check(self, url, method='get',
                            expected_content_type=None, **kwargs):
          
          assert method in ['get', 'post']
          result = self.driver.request(method, url, **kwargs)
          if result.status_code != requests.codes.ok:
              raise RuntimeError('Error requesting %r, status = %d' %
                                 (url, result.status_code))
          if expected_content_type is not None:
              content_type = result.headers.get('content-type', '')
              if not re.match(expected_content_type, content_type):
                  raise RuntimeError(
                      'Error requesting %r, content type %r does not match %r' %
                      (url, content_type, expected_content_type))
          return result
docs: Performs a request, and checks that the status is OK, and that the
          content-type matches expectations.
  
          Args:
            url: URL to request
            method: either 'get' or 'post'
            expected_content_type: prefix to match response content-type against
            **kwargs: passed to the request method directly.
  
          Raises:
            RuntimeError if status_code does not match.