TypeError: Expected a string or unicode object
File "/home/razum2um/learning_python/qt4/tray.py", line 34, in <module>
  [], 0, dbus_interface="org.kde.KNotify")
File "/usr/lib64/python2.6/site-packages/dbus/proxies.py", line 68, in __call__
  return self._proxy_method(*args, **keywords)
File "/usr/lib64/python2.6/site-packages/dbus/proxies.py", line 140, in __call__
  **keywords)
File "/usr/lib64/python2.6/site-packages/dbus/connection.py", line 612, in call_blocking
  message.append(signature=signature, *args)