usbWatcher = nil

function usbDeviceCallback(data)
    if (data["productName"] == "Kinesis Keyboard Hub") then
        if (data["eventType"] == "added") then
          hs.keycodes.setLayout("U.S. International - PC")
        elseif (data["eventType"] == "removed") then
          hs.keycodes.setLayout("Swiss French")
        end
    end
end

usbWatcher = hs.usb.watcher.new(usbDeviceCallback)
usbWatcher:start()