Start two terminal sessions. These will be used to run the NATS request and reply clients.
You should see the message: Listening on [help.please]
This means that the NATS receiver client is listening for request messages on the "help.please" subject. In NATS, the receiver is a subscriber.
The NATS requestor client makes a request by sending the message "I need help!" on the “help.please” subject.
The NATS receiver client receives the message, formulates the reply ("OK, I CAN HELP!!!"), and sends it to the inbox of the requester.