How to create global dispatch queue

GlobalDispatchQueue.swift

let dispatchQueue = DispatchQueue(label: "Background", attributes: .concurrent)
dispatchQueue.async {
    for i in 0..<5 {
        print("DispatchQueue X ", i)
    }
}

dispatchQueue.async {
    for i in 5..<10 {
        print("DispatchQueue Y ", i)
    }
}

dispatchQueue.async {
    for i in 10..<15 {
        print("DispatchQueue Z ", i)
    }
}