code: def get_ticker(self, symbol, size=1, _async=False):
          
          params = {'symbol': symbol, 'size': size}
  
          url = u.MARKET_URL + '/market/history/trade'
          return http_get_request(url, params, _async=_async)
docs: 获取历史ticker
          :param symbol:
          :param size: 可选[1,2000]
          :return: