def decrypt(self, encoded_message: str) -> str:
        decoded_message = ""

        # decoding shift like Caesar cipher algorithm implementing negative shift or
        # reverse shift or left shift
        for i in encoded_message:
            position = self.__key_list.index(i)
            decoded_message += self.__key_list[
                (position - self.__shift_key) % -len(self.__key_list)
            ]

        return decoded_message