implement ping functionality

src/server.py

@@ -18,6 +18,9 @@ class Handler_TCPServer(socketserver.BaseRequestHandler):
         # just send back ACK for data arrival confirmation
         self.request.sendall("ACK from TCP Server".encode())
 
+    def ping(self, param):
+        return "PONG"
+
 
 if __name__ == "__main__":
     HOST, PORT = "localhost", 9999