         return zipped
     }
     
-    public static func unzip(_ input: Data) -> Data? {
+    static func unzip(_ input: Data) -> Data? {
         if (input.isEmpty) {
             return nil
         }


class DataChannel {
    
    private let native: RTCDataChannel
    private let delegate: BasicDataChannelDelegate
    
    init(dataChannel: RTCDataChannel, compress: Bool, mediaChannel: MediaChannel?, peerChannel: BasicPeerChannel?) {
        Logger.info(type: .dataChannel, message: "initialize DataChannel: label => \(dataChannel.label), compress => \(compress)")

// https://developer.apple.com/documentation/accelerate/compressing_and_decompressing_data_with_buffer_compression
fileprivate class ZLibUtil {
    
    static func zip(_ input: Data) -> Data? {
        if input.isEmpty {
            return nil
        }
