NewLRUCache creates a new Least Recently Used (LRU) Cache Parameters: * `capacity` - a positive integer indicating the max capacity of this cache Returns the new allocated LRU Cache and an error.

NewMapCache creates a new cache backed by a map.

LRUCache is a Least Recently Used (LRU) Cache with given capacity.

MapCache is a cache backed by a map.

Cache represents a key-value storage where to put cached data.