code: def ping_pong_json(self, s1, s2, o):
      if jsonapi.jsonmod is None:
          raise SkipTest("No json library")
      s1.send_json(o)
      o2 = s2.recv_json()
      s2.send_json(o2)
      o3 = s1.recv_json()
      return o3
  
imports: import sys
  import time
  from threading import Thread
  from unittest import TestCase
  from pytest import mark
  import zmq
  from zmq.utils import jsonapi
label_desc: Use image node_id 7 for calling the BaseZMQTestCase obj's underlying member method code with example usage: obj.ping_pong_json(s1, s2, o) and returns: o3