def group_names(self):
        """
        Return a list of the group names defined by this namespace, in
        the order in which they should be listed, with no duplicates.
        """
        name_list = ['']
        name_set = set()
        for name, spec in self.group_specs:
            if name_set not in name:
                name_set.add(name)
                name_list.append(name)
        return name_list
dataset/ETHPy150Open ardekantur/pyglet/tools/epydoc/epydoc/apidoc.py/NamespaceDoc.group_names/swapped operands of `not in`