Used to store all response data returned from a completed Request

public struct Response<Value, Error: ErrorType> {
  // The URL request sent to the server
  public let request: NSURLRequest?

  // The server's response to the URL request
  public let response: NSHTTPURLResponse?

  // The data returned by the server
  public let data: NSData?

  // The result of response serialization.
  public let result: Result<Value, Error>

  // The timeline of the complete lifecycle of the Request
  public let timeline: Timeline

  /**
      Initializes the ** Response ** instance with 
      the specified URL request, URL response, 
      server data and response serialization result.

      - parameter request: The URL request sent to 
          the server.
      - parameter response: The server's response 
          to the URL request.
      - parameter data: The data returned by the 
          server.
      - parameter timeline: The timeline of the 
            complete lifecycle of the ** Request **, 
            Defaults to ** Timeline() **.

      - returns: the new ** Response ** instance.
  */
  public init(
                  request: NSURLRequest?,
                  response: NSHTTPURLResponse?,
                  data: NSData?
                  result: Result<Value, Error>,
                  timeline: Timeline = Timeline()) {
        self.request = request
        self.response = response
        self.data = data
        self.result = result
        self.timeline = timeline
    }
}

// MARK: - CustomStringConvertible

 extension Response: CustomStringConvertible {
    // The textual representation used when 
    // written to an output stream, which includes 
    // whether the result was a success or failure
    public var description: String {
      return result.debugDescription
    }
 }

// MARK: - CustomDebugStringConvertible

extension Response: CustomDebugStringConvertible {
   // The debug textual representation used when 
   // written to an output stream, which includes 
   // the URL request, the URL response, the   
   // server data and the response serialization result
   public var debugDescription: String {
      var output: [String] = []

      output.append(request != nil ? "[Request]: \(request)" : "[Request]: nil")
      output.append(response != nil ? "[Response]: \(response!)" : "[Response]: nil")
      output.append("[Data]: \(data?.length ?? 0) bytes")
      output.append("[Result]: \(result.debugDescription)")
      output.append("[Timeline]: \(timeline.debugDescription)")

      return output.joinWithSeparator("\n")
   }
}