def process_request(self, request):
        """
        Checks whether the page is already cached and returns the cached
        version if available.
        """
        if not ('GET', 'HEAD') in request.method or request.GET:
            request._cache_update_cache = False
            return None # Don't bother checking the cache.

        cache_key = get_cache_key(request, self.key_prefix)
        if cache_key is None:
            request._cache_update_cache = True
            return None # No cache information available, need to rebuild.

        response = cache.get(cache_key, None)
        if response is None:
            request._cache_update_cache = True
            return None # No cache information available, need to rebuild.

        request._cache_update_cache = False
        return response
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.2/django/middleware/cache.py/FetchFromCacheMiddleware.process_request/swapped operands of `in`