class Test {
    var amountLeftToDownload: Int
    var amountDownloaded: Int

    init(amountLeftToDownload: Int, amountDownloaded: Int) {
        self.amountLeftToDownload = amountLeftToDownload
        self.amountDownloaded = amountDownloaded
    }
}

let totalDownloadsToProcess = progress.reduce(0) {$0.amountLeftToDownload, $0.amountDownloaded }