text: """
  Add helper code to the default IEventSource class.
  """
  from virtualbox import library, events
  
  
  class IEventSource(library.IEventSource):
      __doc__ = library.IEventSource.__doc__
  
      def register_callback(self, callback, event_type):
          """register a callback function for the provided given event_type"""
          return events.register_callback(callback, self, event_type)
  