Attempts to get a response from cache, returns a tuple of the response and whether it's expired
            If there is no cached response return (None, None,)

def get_cache(self, request):
        """ Attempts to get a response from cache, returns a tuple of the response and whether it's expired
            If there is no cached response return (None, None,)
        """

        # try and get the cached GET response
        cache_key = self.cache_key(request)
        cached_response = cache.get(cache_key, None)
        # if it wasn't found and we are looking for a HEAD, try looking for a corresponding GET
        if cached_response is None and request.method == 'HEAD':
            cache_key = self.cache_key(request, 'GET')
            cached_response = cache.get(cache_key, None)
        if cached_response is None:
            return None, None
        if cached_response[1] < time.time() - settings.BETTERCACHE_LOCAL_POSTCHECK:
            return cached_response[0], True
        return cached_response[0], False