import jsonfile = 'favnum.json'def save_fav():    number = input('Type your favourite number: ')    with open(file, 'w') as f:        num = json.dump(number, f)        return numdef get_stored_number():    try:           with open(file) as f:            number_fav = json.load(f)            except FileNotFoundError:        return None    else:        return number_favdef main_number():    num = get_stored_number()        if num:        print('your favourite number is: ')        print(num)        else:        print('the number had not saved before\nthus you have to save it')        numbers = save_fav()        print('your number is saved')        print(numbers)main_number()輸出：the number had not saved beforethus you have to save itType your favourite number: 3.14your number is savedNone