def METHOD_NAME(self):
    try:
        self.netns
    except ex.Error:
        return False
    if self.netns is None:
        return False
    cmd = [Env.syspaths.nsenter, "--net="+self.netns, "ip", "rule", "list"] + self.spec
    out, err, ret = justcall(cmd)
    return ret == 0 and out.strip() != ""