hit(item) {
    if (!this.cache.has(item)) {
      return this
    }

    // remove it first to reorder in lru OrderedSet
    return new LRUCache(this.limit, this.evictCount, this.cache, this.lru.remove(item).add(item))
  }
Updates this cache when it is determined to contain the associated value
@param {Object} item
@return {LRUCache}