Returns a list of the default classes for the tab group.

        Defaults to ``["nav", "nav-tabs", "ajax-tabs"]``.

def get_default_classes(self):
        """Returns a list of the default classes for the tab group.

        Defaults to ``["nav", "nav-tabs", "ajax-tabs"]``.
        """
        default_classes = super(TabGroup, self).get_default_classes()
        default_classes.extend(CSS_TAB_GROUP_CLASSES)
        return default_classes