def METHOD_NAME(json_app: Sanic):
    @json_app.get("/json-append")
    async def handler_append(request: Request):
        return json_response(["a", "b"], status=200)
    @json_app.on_response
    def do_append(request: Request, response: JSONResponse):
        response.append("c")
    _, resp = json_app.test_client.get("/json-append")
    assert resp.body == json_dumps(["a", "b", "c"]).encode()