def _content_function(self):
        """
        This returns a set containing the actively shown module.
        This is so we only get update events triggered for these modules.
        """
        # ensure that active is valid
        self.active = self.active % len(self.items)

        return {self.items[self.active]}

        This returns a set containing the actively shown module.
        This is so we only get update events triggered for these modules.
        
py3status/modules/group.py