def update(self, event, annotation):
        """Update the specified annotation."""
        # Decide whether or not to hide previous highlights...
        for artist in self.highlights.values():
            if self.display == 'multiple':
                continue
            if self.display == 'one-per-axes':
                if event.artist.axes is not artist.axes:
                    continue
            artist.set_visible(False)
        self.show_highlight(event.artist)
        DataCursor.update(self, event, annotation)
Update the specified annotation.