def names(self):
        """
        Get all names of children
        :return:
        :rtype:
        """
        if not self.children:
            return set([self.name])
        ret = set()
        for child in self.children:
            for name in child.names:
                ret.add(name)
        return ret
Get all names of children
        :return:
        :rtype: