docs: public OkCoinPriceLimit getPriceLimits(CurrencyPair currencyPair, Object... args)
        throws IOException {
      if (args != null && args.length > 0)
        return getFuturesPriceLimits(currencyPair, (FuturesContract) args[0]);
      else return getFuturesPriceLimits(currencyPair, futuresContract);
    }