code: function(...args) {
        const cacheKey = keySelector(...args);
  
        if (isValidCacheKey(cacheKey)) {
          let cacheResponse = cache.get(cacheKey);
  
          if (cacheResponse === undefined) {
            cacheResponse = selectorCreator(...funcs);
            cache.set(cacheKey, cacheResponse);
          }
  
          return cacheResponse(...args);
        }
        console.warn(
          `[re-reselect] Invalid cache key "${cacheKey}" has been returned by keySelector function.`
        );
        return undefined;
      }
docs: Application receives this function