New version.swift

func betterDoSomething() throws -> String {
    let success = (arc4random_uniform(2) == 1) // flip a coin
    if success {return "success"} // succeed
    throw Error.Unlucky // fail
}

func client1() throws -> String {
    let string = try betterDoSomething()
    // blah blah other work
    return string
}

func client2() throws -> String {
    let string = try client1()
    // blah blah other work
    return string
}

func consumer() {
    do {
        let string = try client2()
        print("String consumed: \(string)")
    } catch {
        print("Error handled here (\(error))")
    }
}

consumer()