lru/lru.go
func (c *LRU) Purge() {
	for k := range c.items {
		delete(c.items, k)
	}
	c.evictList.Init()
}
func (c *LRU) Purge() {
	for k := range c.items {
		delete(c.items, k)
	}
	c.evictList.Init()
}
// Purge is used to completely clear the cache.