func LRU() Option {
	return func(lc *cacheImpl) error {
		lc.isLRU = true
		return nil
	}
}
LRU sets cache to LRU (Least Recently Used) eviction mode.
package cache
import "time"
type Option func(lc *cacheImpl) error
func OnEvicted(fn func(key string, value interface{})) Option {
	return func(lc *cacheImpl) error {
		lc.onEvicted = fn
		return nil
	}
}
func MaxKeys(max int) Option {
	return func(lc *cacheImpl) error {
		lc.maxKeys = max
		return nil
	}
}
func TTL(ttl time.Duration) Option {
	return func(lc *cacheImpl) error {
		lc.ttl = ttl
		return nil
	}
}