import socketserver = socket.socket()server.bind(('127.0.0.1',9999))server.listen()s, raddr = server.accept()while True:    data = s.recv(1024)    print(data)    s.send('ack. {}'.format(data.decode()).encode())s.close()server.close()

 https://www.bilibili.com/video/av33619067?p=3