code: func (b *LRUCache) Get(key string) (v interface{}, ok bool) {
  	b.lock.Lock()
  	defer b.lock.Unlock()
  
  	e := b.table[key]
  	if e == nil {
  		return nil, false
  	}
  
  	b.touchEntry(e)
  	return e.value, true
  }
docs: // Get a key from the cache, possibly stale. Update its LRU score. O(1)