code: function _initializeCache(options) {
                  this.callbackCache = new Cacher({
                      max: PostMessageUtilities.parseNumber(options.maxConcurrency, DEFAULT_CONCURRENCY),
                      ttl: PostMessageUtilities.parseNumber(options.timeout, DEFAULT_TIMEOUT),
                      interval: CACHE_EVICTION_INTERVAL
                  });
              }
docs: Method for initializing the cache for responses
  @param {Number} [options.maxConcurrency = 100] - optional maximum concurrency that can be managed by the component before dropping
  @param {Number} [options.timeout = 30000] - optional milliseconds parameter for waiting before timeout to responses (default is 30 seconds)
  @private