         }
     }
     
-    private func download(_ item: Item, _ cached: Cached, _ callback: @escaping (Result) -> ()) {
+    private func download(_ item: Item, _ cached: IsCached, _ callback: @escaping (Result) -> ()) {
         guard !canceled else {
             callback(.cancel)
             return

    }
    
    private enum ContentLengthResult {
        case success(Int64?, [Cached])
        case canceled
        case failure(Error)
    }

import Foundation

private typealias IsCached = Bool

public class Downloader {
    public let items: [Item]
