docs: public Map<Currency, Map<Currency, BigDecimal>> getCurrencyCoinRate(CurrencyPair... currencyPairs)
        throws IOException {
      List<String> coinList = new ArrayList<>(currencyPairs.length);
      Arrays.stream(currencyPairs)
          .forEach(currencyPair -> coinList.add(currencyPair.base.getCurrencyCode().toLowerCase()));
      String coins = coinList.stream().collect(Collectors.joining(","));
      return bitz.getCurrencyCoinRate(coins).getData();
    }