':param Answer answer: èŠæ²¡æåž®å©æåæ¶æ²¡æåž®å©åç­
:param unhelpful: True-->æ²¡æåž®å©ïŒFalse-->åæ¶æ²¡æåž®å©
:return: æåè¿å TrueïŒå€±èŽ¥è¿å False
:rtype: bool'

def unhelpful(self, answer, unhelpful=True):

    from .answer import Answer
    if (isinstance(answer, Answer) is False):
        raise ValueError('argument    answer    need    to    be    Zhihu.Answer    object.')
    if (answer.author.url == self.url):
        return False
    data = {'_xsrf': answer.xsrf, 'aid': answer.aid}
    res = self._session.post((Unhelpful_Url if unhelpful else Cancel_Unhelpful_Url), data=data)
    return (res.json()['r'] == 0)
