code: func (c *ARCCache) Peek(key interface{}) (value interface{}, ok bool) {
  	c.lock.RLock()
  	defer c.lock.RUnlock()
  	if val, ok := c.t1.Peek(key); ok {
  		return val, ok
  	}
  	return c.t2.Peek(key)
  }
docs: // Peek is used to inspect the cache value of a key
  // without updating recency or frequency.