code: def get_group_tabs(self):
          
          if self.tab_group is None:
              raise ImproperlyConfigured(
                  "%s requires a definition of 'tab_group'" %
                  self.__class__.__name__)
          group_members = [t for t in self._registry if t.tab_group == self.tab_group]
          return [t() for t in group_members]
docs: Return instances of all other tabs that are members of the tab's
          tab group.