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

        Defaults to and empty list (``[]``), however additional classes may
        be added depending on the state of the tab as follows:

        If the tab is the active tab for the tab group, in which
        the class ``"active"`` will be added.

        If the tab is not enabled, the classes the class ``"disabled"``
        will be added.
        """
        default_classes = super(Tab, self).get_default_classes()
        if self.is_active():
            default_classes.extend(CSS_ACTIVE_TAB_CLASSES)
        if not self._enabled:
            default_classes.extend(CSS_DISABLED_TAB_CLASSES)
        return default_classes