Can't return results to method via completion handler.

import Foundation

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

// Add your code below
func fetchTreehouseBlogPosts (completion: BlogPostCompletion) {
  let blogURL = NSURL(string: "http://blog.teamtreehouse.com/api/")
  let requestURL = NSURL(string: "get_recent_summary/?count=20", relativeToURL: blogURL)

  let request = NSURLRequest(URL: requestURL!)

  let config = NSURLSessionConfiguration.defaultSessionConfiguration()
  let session = NSURLSession(configuration: config)

  // Add your code between the comments
  let dataTask = session.dataTaskWithRequest(request) {
    (let data, let response, let error) in
    completion(data)
  }
  // Add code above

  dataTask.resume()
}