code: def on_click(self, handler):
          ''' Set up a handler for button or menu item clicks.
  
          Args:
              handler (func) : handler function to call when button is activated.
  
          Returns:
              None
  
          '''
          self.on_event(ButtonClick, handler)
          self.on_event(MenuItemClick, handlerf on_click(self, handler):
          ''' Set up a handler for button or menu item clicks.
  
          Args:
              handler (func) : handler function to call when button is activated.
  
          Returns:
              None
  
          '''
          self.on_event(ButtonClick, handler)
          self.on_event(MenuItemClick, handler)
docs: Set up a handler for button or menu item clicks.
  
          Args:
              handler (func) : handler function to call when button is activated.
  
          Returns:
              None