Swift Setup for the HackerRank Environment

HackerRankSetup.Swift

func multiLineInputSetup() {
//Use this for multiple line inputs. The problem for which I generated this had the first term in its sequence as the number of lines of input. If this isn't available, you could just build a while loop that switches on whether a string can be instantiated with readLine()
    let fileName = ProcessInfo.processInfo.environment["OUTPUT_PATH"]!
    FileManager.default.createFile(atPath: fileName, contents: nil, attributes: nil)
    let fileHandle = FileHandle(forWritingAtPath: fileName)!

    guard let s = readLine(), let count = Int(s) else { fatalError("Bad input") }
    var output = ""
        for _ in 1...count {
        guard let s = readLine() else {continue}
        let result = run(s)
        if let result = result { output.append(result) }
    }
    fileHandle.write(output.data(using: .utf8)!)
}

func singleLineInputSetup() {
//Alternatively if there's just a single line of input, use this setup
    let fileName = ProcessInfo.processInfo.environment["OUTPUT_PATH"]!
    FileManager.default.createFile(atPath: fileName, contents: nil, attributes: nil)
    let fileHandle = FileHandle(forWritingAtPath: fileName)!

    guard let s = readLine() else { fatalError("Bad input") }
    let output = run(input: s)
    fileHandle.write(output.data(using: .utf8)!)
}

func run(input: String)-> String {
//Be sure to copy this function in either case and have any output that needs to be written to STDOUT returned as a String
    var output = ""
    //Do the thing here
    return output
}