code: func (c *LRU) Peek(key interface{}) (value interface{}, ok bool) {
  	var ent *list.Element
  	if ent, ok = c.items[key]; ok {
  		return ent.Value.(*entry).value, true
  	}
  	return nil, ok
  }
docs: // Peek returns the key value (or undefined if not found) without updating
  // the "recently used"-ness of the key.