code: def get_last_depth(self, symbol, _type, _async=False):
          
          params = {'symbol': symbol, 'type': _type}
  
          url = u.MARKET_URL + '/market/depth'
          return http_get_request(url, params, _async=_async)
docs: 获取marketdepth
          :param symbol
          :param type: 可选值：{ percent10, step0, step1, step2, step3, step4, step5 }
          :return: