我正在嘗試使用類和函數向字符串中每兩個字母添加一個隨機字母class Encryption():    def __init__(self,seed):        # Set a random seed and a self.seed attribute        self.seed = seed        # Create an empty string attribute to hold the encrypted phrase        self.encrypted_phrase = ''        # Use the string and random libraries to create two attributes        # One is the correct alphabet, another is a shuffled alphabet:        self.correct_alphabet = list(string.ascii_lowercase)        self.shuffeled_alphabet = random.sample(correct_alphabet, seed)    def encryption(self,message):        appended_message = list(message)               for let in list(range(0, len(message), 2)):            if let in self.correct_alphabet:                appended_message.append(self.shuffeled_alphabet)        return appended_message所以如果我這樣做e2 = Encryption(3)e2.encryption(hello)它失敗并顯示以下消息NameError                                 Traceback (most recent call last)<ipython-input-24-505d8a880fb2> in <module>----> 1 e2.encryption(message=hello)NameError: name 'hello' is not defined我究竟做錯了什么？