docs: def server(addr):
          """Return a SocketTalk server."""
          sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
          sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
          sock.bind(addr)
          sock.listen(1)
          conn, addr = sock.accept()
          talk = SocketTalk(conn)
          return talk