diff --git a/examples/Plugin.ipynb b/examples/Plugin.ipynb
index cb44668..be0ce35 100644
--- a/examples/Plugin.ipynb
+++ b/examples/Plugin.ipynb
@@ -163,9 +163,9 @@
     "\n",
     "class PileupTrack(hg.PluginTrack):\n",
     "    type: Literal[\"pileup\"]\n",
-    "    plugin_url: ClassVar[\n",
-    "        str\n",
-    "    ] = \"https://unpkg.com/higlass-pileup/dist/higlass-pileup.min.js\"\n",
+    "    plugin_url: ClassVar[str] = (\n",
+    "        \"https://unpkg.com/higlass-pileup/dist/higlass-pileup.min.js\"\n",
+    "    )\n",
     "\n",
     "\n",
     "hg.Viewconf[Union[PileupTrack, hg.Track]](**config)  # works!"
@@ -217,9 +217,9 @@
     "        \"horizontal-stacked-bar\",\n",
     "        \"basic-multiple-bar-chart\",\n",
     "    ]\n",
-    "    plugin_url: ClassVar[\n",
-    "        str\n",
-    "    ] = \"https://unpkg.com/higlass-multivec/dist/higlass-multivec.min.js\""
+    "    plugin_url: ClassVar[str] = (\n",
+    "        \"https://unpkg.com/higlass-multivec/dist/higlass-multivec.min.js\"\n",
+    "    )"
    ]
   },
   {
@@ -279,9 +279,9 @@
     "        \"horizontal-stacked-bar\",\n",
     "        \"basic-multiple-bar-chart\",\n",
     "    ]\n",
-    "    plugin_url: ClassVar[\n",
-    "        str\n",
-    "    ] = \"https://unpkg.com/higlass-multivec/dist/higlass-multivec.min.js\"\n",
+    "    plugin_url: ClassVar[str] = (\n",
+    "        \"https://unpkg.com/higlass-multivec/dist/higlass-multivec.min.js\"\n",
+    "    )\n",
     "\n",
     "\n",
     "track = MultivecTrack(\n",
@@ -360,9 +360,9 @@
     "class SequenceTrack(hg.PluginTrack):\n",
     "    type: Literal[\"horizontal-sequence\"]\n",
     "    data: Optional[SeqeuenceTrackData] = None\n",
-    "    plugin_url: ClassVar[\n",
-    "        str\n",
-    "    ] = \"https://unpkg.com/higlass-sequence/dist/higlass-sequence.js\"\n",
+    "    plugin_url: ClassVar[str] = (\n",
+    "        \"https://unpkg.com/higlass-sequence/dist/higlass-sequence.js\"\n",
+    "    )\n",
     "\n",
     "\n",
     "track = SequenceTrack(\n",
diff --git a/pyproject.toml b/pyproject.toml
index 37d5371..0247b7e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -28,7 +28,7 @@ readme = "README.md"
 dependencies = [
     "servir>=0.0.5",
     "higlass-schema>=0.0.6",
-    "anywidget>=0.6.3",
+    "anywidget>=0.9.0",
     "jinja2",
     "jupyter-server-proxy>=3.0",
     "typing-extensions ; python_version<'3.9'",
@@ -74,6 +74,7 @@ test = "pytest ."
 
 [tool.hatch.envs.docs]
 features = ["docs"]
+python = "3.11"
 
 [tool.hatch.envs.docs.scripts]
 build = "sphinx-build -b html ./docs ./docs/_build/html"
diff --git a/src/higlass/api.py b/src/higlass/api.py
index 5bffcf9..c2eb2ad 100644
--- a/src/higlass/api.py
+++ b/src/higlass/api.py
@@ -649,18 +649,17 @@ class _TrackCreator(BaseModel):
 
 
 @overload
-def track(type_: hgs.EnumTrackType, uid: str | None = None, **kwargs) -> EnumTrack:
-    ...
+def track(type_: hgs.EnumTrackType, uid: str | None = None, **kwargs) -> EnumTrack: ...
 
 
 @overload
-def track(type_: Literal["heatmap"], uid: str | None = None, **kwargs) -> HeatmapTrack:
-    ...
+def track(
+    type_: Literal["heatmap"], uid: str | None = None, **kwargs
+) -> HeatmapTrack: ...
 
 
 @overload
-def track(type_: str, uid: str | None = None, **kwargs) -> PluginTrack:
-    ...
+def track(type_: str, uid: str | None = None, **kwargs) -> PluginTrack: ...
 
 
 def track(
diff --git a/src/higlass/widget.js b/src/higlass/widget.js
index 7e84d25..3a4b6dd 100644
--- a/src/higlass/widget.js
+++ b/src/higlass/widget.js
@@ -12,7 +12,7 @@ function toPts({ xDomain, yDomain }) {
   return [x, xe, y, ye];
 }
 
-export async function render({ model, el }) {
+async function render({ model, el }) {
   let viewconf = model.get("_viewconf");
   let options = model.get("_options") ?? {};
   let api = await hglib.viewer(el, viewconf, options);
@@ -39,3 +39,5 @@ export async function render({ model, el }) {
     });
   }
 }
+
+export default { render };