<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 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