 }
 
 
-public class InMemoryCache: Cache {
+open class InMemoryCache: Cache {
     private var cache = Dictionary<String, (response: SwiftLinkPreview.Response, date: Date)>()
     private let invalidationTimeout: TimeInterval
     private let cleanupTimer: DispatchSource

        }
    }
    
    public func slp_getCachedResponse(url: String) -> SwiftLinkPreview.Response? {
        return type(of: self).cacheQueue.sync {
            guard let response = cache[url] else { return nil }
            

        }
    }
    
    open func slp_setCachedResponse(url: String, response: SwiftLinkPreview.Response?) {
        type(of: self).cacheQueue.sync {
            if let response = response {
                cache[url] = (response, Date())
