def ui_modify_data(l):
    processing_functions = [ui_add_package, ui_print_package]
    progress = 0
    while progress < len(processing_functions):
        cmd = input("Reintroduce dates: ")
        if cmd == "//":
            progress -= 1
            print("Go back to previous input")
        else:
            print("Processing" + cmd)
            processing_functions[progress](cmd)
            progress += 1