diff --git a/docs/nb.ipynb b/docs/nb.ipynb
index 4b3d844..9350ffd 100644
--- a/docs/nb.ipynb
+++ b/docs/nb.ipynb
@@ -15,8 +15,10 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from dargs.sphinx import _test_argument\n",
+    "from __future__ import annotations\n",
+    "\n",
     "from dargs.notebook import JSON\n",
+    "from dargs.sphinx import _test_argument\n",
     "\n",
     "jstr = \"\"\"\n",
     "{\n",