Upvote the currently selected item.

def upvote(self):
        """
        Upvote the currently selected item.
        """
        data = self.get_selected_item()
        if 'likes' not in data:
            self.term.flash()
        elif getattr(data['object'], 'archived'):
            self.term.show_notification("Voting disabled for archived post", style='Error')
        elif data['likes']:
            with self.term.loader('Clearing vote'):
                data['object'].clear_vote()
            if not self.term.loader.exception:
                data['likes'] = None
        else:
            with self.term.loader('Voting'):
                data['object'].upvote()
            if not self.term.loader.exception:
                data['likes'] = True