def toggle_extra_file_widgets(self):
        """Toggle presence of widgets to pick file to load."""
        widgets = self.widgets
        file_to_load_widgets = self.file_to_load_widgets

        if file_to_load_widgets[0] in widgets:
           for obj in file_to_load_widgets:
                widgets.remove(obj)
        else:
            widgets.extend(file_to_load_widgets)
Toggle presence of widgets to pick file to load.
nodezator/editing/playback/demonstrate/__init__.py