         @param storagePolicy an NSURLCacheStoragePolicy constant.
         @result an initialized NSCachedURLResponse.
     */
-    public init(response: URLResponse, data: NSData, userInfo: [NSObject : AnyObject]?, storagePolicy: URLCache.StoragePolicy) { NSUnimplemented() }
+    public init(response: URLResponse, data: NSData, userInfo: [NSObject : AnyObject]? = [:], storagePolicy: URLCache.StoragePolicy) { NSUnimplemented() }
     
     /*! 
         @method response

     @method removeCachedResponsesSince:
     @abstract Clears the given cache of any cached responses since the provided date.
     */
    public func removeCachedResponsesSinceDate(_ date: Date) { NSUnimplemented() }
    
    /*! 
        @method memoryCapacity

        request, or nil if there is no NSCachedURLResponse stored with the
        given request.
    */
    public func cachedResponse(for request: URLRequest) -> CachedURLResponse? { NSUnimplemented() }
    
    /*! 
        @method storeCachedResponse:forRequest:
