 /// Response cache handles the storage of JSON response dictionaries indexed by their associated `Request`.  It contains both memory and disk caching functionality
 final internal class ResponseCache
 {
+    struct Constant
+    {
+        static let cacheDirectory = "com.vimeo.Caches"
+    }
+    
     /**
      Stores a response dictionary for a request.
      

                
                do
                {
                    if !fileManager.fileExistsAtPath(directoryPath)
                    {
                        try fileManager.createDirectoryAtPath(directoryPath, withIntermediateDirectories: true, attributes: nil)
                    }

        
        private func cachesDirectoryURL() -> NSURL
        {
            // Apple /Caches directory
            guard let directory = NSSearchPathForDirectoriesInDomains(.CachesDirectory, .UserDomainMask, true).first
            else
            {
                fatalError("no cache directories found")
            }
            
            // We need to create a directory in `../Library/Caches folder`. Otherwise, trying to remove the Apple /Caches folder will always fails. Note that it's noticeable while testing on a device.
            let cacheDirectory = directory + Constant.cacheDirectory
            
            return NSURL(fileURLWithPath: cacheDirectory)
        }
        
        private func fileURLForKey(key key: String) -> NSURL?
