Return a SocketTalk server.

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