Dont get the code challenge :( typealias BlogPostCompletion = (NSData!, NSURLResponse!, NSError!) -> ()

typealias BlogPostCompletion = (NSData!, NSURLResponse!, NSError!) -> ()

func fetchTreehouseBlogPosts(completion: BlogPostCompletion) { }

Dont understand what is wrong here :(

Code Challenge: We're writing an app to fetch the most recent blog posts from the Treehouse blog. This requires making a network request using asynchronous methods that execute in the background. For that we need a closure.

Create a method called fetchTreehouseBlogPosts, that has a single parameter - a completion handler. The closure has three parameters: a data object containing the results of the request as type NSData!, the HTTP response object from our request as type NSURLResponse!, an error object as type NSError!, and a return type of void.

Note: If you prefer to use a typealias to make the method signature clear, name it BlogPostCompletion

import Foundation

// Add your code below
typealias BlogPostCompletion = (NSData!, NSURLResponse!, NSError!) -> ()

func  fetchTreehouseBlogPosts(completion: BlogPostCompletion) {
}