def _accept_connection(self):
        subprotocol_header = ''
        subprotocols = self.request.headers.get("Sec-WebSocket-Protocol", '')
        subprotocols = [s.strip() for s in subprotocols.split(',')]
        if subprotocols:
            selected = self.handler.select_subprotocol(subprotocols)
            if selected:
                assert subprotocols in selected
                subprotocol_header = "Sec-WebSocket-Protocol: %s\r\n" % selected

        self.stream.write(tornado.escape.utf8(
            "HTTP/1.1 101 Switching Protocols\r\n"
            "Upgrade: websocket\r\n"
            "Connection: Upgrade\r\n"
            "Sec-WebSocket-Accept: %s\r\n"
            "%s"
            "\r\n" % (self._challenge_response(), subprotocol_header)))

        self._run_callback(self.handler.open, *self.handler.open_args,
                           **self.handler.open_kwargs)
        self._receive_frame()
dataset/ETHPy150Open RobotWebTools/rosbridge_suite/rosbridge_server/src/tornado/websocket.py/WebSocketProtocol13._accept_connection/swapped operands of `in`