'å·æ° Answer object çå±æ§.
äŸåŠèµåæ°å¢å äº, åè°çš ``refresh()``
åè®¿é® upvote_numå±æ§, å¯è·åŸæŽæ°åçèµåæ°.
:return: None'

def refresh(self):

    super().refresh()
    self._html = None
    self._upvote_num = None
    self._content = None
    self._collect_num = None
    self._comment_num = None
