import socket

udp_server = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
udp_server.bind(("127.0.0.1", 20001))

data, client_address = udp_server.recvfrom(1024)
print('Server: data received from the client at ' + str(client_address) + ':', data.decode())

message = 'Hello the from UDP server'
udp_server.sendto(message.encode(), client_address)