let filePath: String = NSString(string: "~/Desktop/del.txt").expandingTildeInPath
guard let data: Data = ("black dog" as NSString).data(using: String.Encoding.utf8.rawValue) else {Swift.print("unable to create data");return}
FSWriter.write(url: URL(filePath), data: data, index: 0)

let filePath: String = NSString(string: "~/Desktop/del.txt").expandingTildeInPath
let data: Data = FSReader.read(filePath: filePath, startIndex: 50, endIndex: 100)
Swift.print("\(String(data: data, encoding: .utf8))") // blalbslalballabalbla...

let fileSize = FSReader.fileSize(filePath: filePath)