code: def find_path(self, symbol=None, subdir='lday', ext='day'):
          '''
          寻找文件路径，辅助函数
  
          :param symbol:
          :param subdir:
          :param ext:
          :return: pd.dataFrame or None
          '''
          market = get_stock_market(symbol, True)
          ext = ext if isinstance(ext, list) else [ext]
  
          for t in ext:
              vipdoc = 'vipdoc/{}/{}/{}{}.{}'.format(market, subdir, market, symbol, t)
              vipdoc = os.path.join(self.tdxdir, vipdoc)
  
              if os.path.exists(vipdoc):
                  return vipdoc
  
          return Nonf find_path(self, symbol=None, subdir='lday', ext='day'):
          '''
          寻找文件路径，辅助函数
  
          :param symbol:
          :param subdir:
          :param ext:
          :return: pd.dataFrame or None
          '''
          market = get_stock_market(symbol, True)
          ext = ext if isinstance(ext, list) else [ext]
  
          for t in ext:
              vipdoc = 'vipdoc/{}/{}/{}{}.{}'.format(market, subdir, market, symbol, t)
              vipdoc = os.path.join(self.tdxdir, vipdoc)
  
              if os.path.exists(vipdoc):
                  return vipdoc
  
          return None
docs: 寻找文件路径，辅助函数
  
          :param symbol:
          :param subdir:
          :param ext:
          :return: pd.dataFrame or None