old_contents: from virtualbox import library
  
  
  """
  Add helper code to the default IMouse class.
  """
  
  
  class IMouse(library.IMouse):
      __doc__ = library.IMouse.__doc__
  
      def register_on_guest_mouse(self, callback):
          """Set the callback function to consume on guest mouse events.
          
          Callback receives a IGuestMouseEvent object.
  
          Example:
              def callback(event):
                  print(("%s %s %s" % (event.x, event.y, event.z))     
          """
          return self.event_source.register_callback(callback, 
                              library.VBoxEventType.on_guest_mouse)
  
  
new_contents: """
  Add helper code to the default IMouse class.
  """
  
  from virtualbox import library
  
  
  class IMouse(library.IMouse):
      __doc__ = library.IMouse.__doc__
  
      def register_on_guest_mouse(self, callback):
          """Set the callback function to consume on guest mouse events.
  
          Callback receives a IGuestMouseEvent object.
  
          Example:
              def callback(event):
                  print(("%s %s %s" % (event.x, event.y, event.z))
          """
          event_type = library.VBoxEventType.on_guest_mouse
          return self.event_source.register_callback(callback, event_type)
  
subject: Fix linting issues in virtualbox/library_ext/mouse.py