Mine

    def _remove_plot_object_canvas_item(self, plot_object):        ## XXX stupid goocanvas API forces us to search for the item        item_to_remove = plot_object.get_canvas_item()        for i in range(self.get_n_children()):            item = self.get_child(i)            if item is item_to_remove:                self.remove_child(i)                break        else:            raise ValueError