code: public List<OkCoinKline> getKlines(CurrencyPair currencyPair, OkCoinKlineType type)
        throws IOException {
      return getKlines(currencyPair, type, null, null);
    }
docs: 获取OKEx币币K线数据(每个周期数据条数2000左右)
  
  @param currencyPair
  @param type
  @return
  @throws IOException