Crypto pricing for Google Sheets

Code.gs

/**
 * Crypto pricing for Google Sheets. Caches values for 10 minutes.
 *
 * Tools -> Script editor, paste this in.
 * Create and populate the API key below.
 *
 * https://www.cryptocompare.com/coins/guides/how-to-use-our-api/
 */

var CC_API_KEY="";
var CACHE_REFRESH=10 * 60;

/**
 * =VALUE(CRYPTO("BTC", "USDT", $A$1))
 *
 * @param {string} from from symbol
 * @param {string} to to symbol
 * @return the current price
 * @customfunction
 */
function CRYPTO(from, to) {
  return _loadStuff("https://min-api.cryptocompare.com/data/price?fsym=" + from + "&tsyms=" + to + "&api_key=" + CC_API_KEY, to, from + to);
}

function _loadStuff(url, key, cacheKey) {
  var cache = CacheService.getScriptCache();
  var cached = cache.get(cacheKey);
  if (cached) {
    return cached;
  }
  var jsondata = UrlFetchApp.fetch(url);
  var contentText = jsondata.getContentText();
  var parsed = JSON.parse(contentText);
  var result = -1;
  if (parsed['Response'] != 'Error') {
    result = parsed[key];
    cache.put(cacheKey, result, CACHE_REFRESH);
  }
  return result;
}

/**
 * For easier debugging in the script editor.
 */
function BTCUSDT() {
  return CRYPTO('BTC', 'USDT');
}