         imagesByUrl.removeAllObjects()
     }
 
-    @warn_unused_result
     private func cachedInDBImageDataStreamForUrl(url: NSURL) -> AsyncStream<(UIImage, NSData), AnyObject, ErrorWithContext> {
 
         let dataStream = network.dataStream(url, postData: nil, headers: nil).mapNext { info -> AnyObject in

            super.init(cacheFactory: cacheFactory, cacheQueueName: cacheQueueName)
        }

        @warn_unused_result
        override func loaderToSetData(data: NSData, forKey key: String) -> AsyncStream<Void, AnyObject, ErrorWithContext> {

            let stream = super.loaderToSetData(data, forKey:key)
            return Transformer.transformStreamsType(stream, transformer: balanced)
        }

        @warn_unused_result
        override func cachedDataStreamForKey(key: String) -> AsyncStream<(date: NSDate, data: NSData), AnyObject, ErrorWithContext> {

            let stream = super.cachedDataStreamForKey(key)

        return stream.logError()
    }

    public func imageStreamForUrl(url: NSURL?) -> AsyncStream<UIImage, AnyObject, ErrorWithContext> {

        guard let url = url where !url.isNoImageDataURL else {
