docs: function requestMp3Url(hypemId, hypemKey, callback) {
          var options = {
              method: "GET",
              url: HYPEM_SERVE_URL + hypemId + "/" + hypemKey,
              headers: {"Cookie": COOKIE},
              timeout: FIVE_SECONDS_IN_MILLIS
          };
  
          request(options, function (error, response) {
              if (!error && response.statusCode === 200) {
                  try {
                      // the request got a json from hypem
                      // where the link to the mp3 file is saved
                      var jsonBody = JSON.parse(response.body);
                      var mp3Url = jsonBody.url;
                      callback(null, mp3Url);
                  } catch (error) {
                      callback(error, null);
                  }
              } else {
                  callback(new Error("Nothing found: " + options.url), null);
              }
          });
      }