What is the worst-time complexity of the following function if the input list is of size n?

def mystery(my_list: ArrayList) -> None:
    my_queue = Queue(len(my_list) * 2)
    for item in my_list:
        my_queue.append(item)
        my_queue.append(item)
    while not my_queue.is_empty():
        print(my_queue.serve())