code: func (c *LRUExpireCache) Get(key interface{}) (interface{}, bool) {
  	c.lock.Lock()
  	defer c.lock.Unlock()
  	e, ok := c.cache.Get(key)
  	if !ok {
  		return nil, false
  	}
  	if c.clock.Now().After(e.(*cacheEntry).expireTime) {
  		c.cache.Remove(key)
  		return nil, false
  	}
  	return e.(*cacheEntry).value, true
  }
docs: // Get returns the value at the specified key from the cache if it exists and is not
  // expired, or returns false.