code: private function fromCache($key, callable $closure)
      {
          $item = $this->cache->fetch($key);
          if ($item === false) {
              $item = $closure();
              $this->cache->save($key, $item);
          }
  
          return $item;
      }
docs: Returns an item from cache or computes it using $closure and puts it in cache.
  
  @param string   $key
  @param callable $closure
  
  @return mixed