This package is a protcol oriented cache implementation with a centrailized feature of expiration. Expiration is optional by definition of the protocol, but not the original intention. The only included implemenation is DictionaryCache, which is in fact thread safe.
var dictCache = DictionaryCache()
dictCache.set("My Object", for: "My Key", expiring: 500)
dictCache["My Key"] // "My Object"