     - returns: Observable sequence of URL responses.
     */
     @warn_unused_result(message="http://git.io/rxs.uo")
-    public func rx_response(request: NSURLRequest) -> Observable<(NSData!, NSHTTPURLResponse)> {
+    public func rx_response(request: NSURLRequest) -> Observable<(NSData, NSHTTPURLResponse)> {
         return create { observer in
 
             // smart compiler should be able to optimize this out

                    return
                }

                observer.on(.Next(data as NSData!, httpResponse))
                observer.on(.Completed)
            }


                    print(convertURLRequestToCurlCommand(request))
                    print(convertResponseToString(data, response, error, interval))
                }
                
                

                guard let response = response, data = data else {
                    observer.on(.Error(error ?? RxCocoaURLError.Unknown))
