'Sends a GET request to url404.
:return: The HTTP response body.'

@retry(tries=2, delay=0.5, backoff=2)
def _send_404(self, url404):

    try:
        response = self._uri_opener.GET(url404, cache=False, grep=False)
    except HTTPRequestException as hre:
        message = 'Exception    found    while    detecting    404:    "%s"'
        raise FourOhFourDetectionException((message % hre))
    return response
