오류 문의

AttributeError                            Traceback (most recent call last)
<ipython-input-7-ba1dbc95b463> in <module>
      1 #잔고조회
----> 2 result = up.get_balances()
      3 result

~\anaconda3\lib\site-packages\pyupbit\exchange_api.py in get_balances(self)
    141         '''
    142         url = "https://api.upbit.com/v1/accounts"
--> 143         headers = self._request_headers()
    144         return _send_get_request(url, headers=headers)
    145 

~\anaconda3\lib\site-packages\pyupbit\exchange_api.py in _request_headers(self, data)
    105         if data is not None:
    106             payload['query'] = urlencode(data)
--> 107         jwt_token = jwt.encode(payload, self.secret, algorithm="HS256").decode('utf-8')
    108         authorization_token = 'Bearer {}'.format(jwt_token)
    109         headers = {"Authorization": authorization_token}

AttributeError: 'str' object has no attribute 'decode'

라고 나오는데 어떻게 처리하면 되나요?