Can a single node act as publisher and subscriber alternativelye

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I want to write two nodes such that each node sends a message alternatively in recurrent cycle and the message contains one string message and two age variables. For example, Node 1 sends a message to Node 2 (Node 1 Publisher, Node 2 Subscriber, node 1 age ++), then after receiving the message Node 2 sends the message back to Node 1 (Node 2 Publisher, Node 1 Subscriber, node 2 age ++) and this cycle continues. I am new to ROS, please help me to design this code in python or c++.

#!/usr/bin/env python
import rospy
from beginner_tutorials.msg import Num

def talker():
    pub = rospy.Publisher('custom_Chat', Num,queue_size=1
)
    rospy.init_node('custom_Node1', anonymous=True)
    msg = Num()
    msg.message = "Message sent to Node2"
    msg.age1 =0
    msg.age2=0
    msg.flag=1
    if msg.flag==1:
        msg.age2+=1
        print ("Hello! this is node 1!!")   
    rospy.loginfo(msg)
    pub.publish(msg)        

if __name__ == '__main__':
    try:
        talker()
    except rospy.ROSInterruptException: pass

......................................................................................................................................................................

#!/usr/bin/env python
import rospy
from beginner_tutorials.msg import Num

def callback(data):
    rospy.loginfo("Hello!this is node2")
    rospy.loginfo("I heard the message %s. %d is my age." % (data.message, data.age2))
    data.age1+=1
    data.flag=2


def listener():
    rospy.init_node('custom_Node2', anonymous=True)
    rospy.Subscriber("custom_Chat", Num, callback)

    # spin() simply keeps python from exiting until this node is stopped
    rospy.spin()

if __name__ == '__main__':
    listener()