code: func (r *Cache) EvictNS(ns uint64) {
  	r.mu.RLock()
  	defer r.mu.RUnlock()
  	if r.closed {
  		return
  	}
  
  	if r.cacher != nil {
  		r.cacher.EvictNS(ns)
  	}
  }
docs: // EvictNS evicts 'cache node' with the given namespace. This will
  // simply call Cacher.EvictNS.