In order to see the client/server interactions, launch the following server script in one console:

$ python 1_14a_echo_server_udp.py --port=9900 
Starting up echo server on localhost port 9900
Waiting to receive message from client
  

Now, run the client from another terminal as follows:

$ python 1_14b_echo_client_udp.py --port=9900 
Connecting to localhost port 9900
Sending Test message. This will be echoed
received Test message. This will be echoed
Closing connection to the server
    
  

Upon receiving the message from the client, the server will also print something similar to the following message:

received 33 bytes from ('127.0.0.1', 43542)
Data: Test message. This will be echoed
sent 33 bytes back to ('127.0.0.1', 43542)
Waiting to receive message from client