         return nsp + "#" + (engine?.sid ?? "")
     }
 
-    private let emitQueue = DispatchQueue(label: "com.socketio.emitQueue", attributes: DispatchQueueAttributes.serial)
+    private let emitQueue = DispatchQueue(label: "com.socketio.emitQueue", attributes: .serial)
     private let logType = "SocketIOClient"
-    private let parseQueue = DispatchQueue(label: "com.socketio.parseQueue", attributes: DispatchQueueAttributes.serial)
+    private let parseQueue = DispatchQueue(label: "com.socketio.parseQueue", attributes: .serial)
 
     private var anyHandler: ((SocketAnyEvent) -> Void)?
     private var currentReconnectAttempt = 0

        self.options = options
        self.socketURL = socketURL
        
        if ((socketURL.absoluteString?.hasPrefix("https://")) != nil) {
            self.options.insertIgnore(.secure(true))
        }
        

        let handler = SocketEventHandler(event: event, id: UUID(), callback: callback)
        handlers.append(handler)

        return handler.id
    }

    /// Adds a single-use handler for an event.
