def load(self):
        if os.path.exists(self.path):
            with open(self.path, 'r') as f:
                self.body_labels = collections.OrderedDict(json.load(f))
def object_id(self):
        return ("ip-path-mtu-%d-%s-%d" % (self.table_id,
                                          self.nh,
                                          self.pmtu))