code: func (l *LRU) Set(key string, val interface{}) error {
  	l.Lock()
  	defer l.Unlock()
  
  	return l.cache.Set(key, val)
  }
docs: // Set sets or overrides the given key with the given value, every set item will
  // be moved or prepended to the head of the linked list for keeping track of
  // least recent used item. When the cache is full, last item of the linked list
  // will be evicted from the cache