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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _req_lixian_task_lists(self, page=1):
 """ This request will cause the system to create a default downloads directory if it does not exist """

        url = 'http://115.com/lixian/'
        params = {'ct': 'lixian', 'ac': 'task_lists'}
        self._load_signatures()
        data = {
            'page': page,
            'uid': self.user_id,
            'sign': self._signatures['offline_space'],
            'time': self._lixian_timestamp,
        }
        req = Request(method='POST', url=url, params=params, data=data)
        res = self.http.send(req)
        if res.state:
            self._task_count = res.content['count']
            self._task_quota = res.content['quota']
            return res.content['tasks']
        else:
            msg = 'Failed to get tasks.'
            raise RequestFailure(msg)