diff --git a/docs/notebooks/simulation_basics.ipynb b/docs/notebooks/simulation_basics.ipynb
index c3073de83..bbde14b07 100644
--- a/docs/notebooks/simulation_basics.ipynb
+++ b/docs/notebooks/simulation_basics.ipynb
@@ -2,18 +2,10 @@
  "cells": [
   {
    "cell_type": "code",
-   "execution_count": 1,
-   "id": "8163b0cd-276a-4530-99dd-97bc20906b78",
+   "execution_count": null,
+   "id": "0",
    "metadata": {},
-   "outputs": [
-    {
-     "name": "stdout",
-     "output_type": "stream",
-     "text": [
-      "\u001b[32m2024-05-23 17:10:58.325\u001b[0m | \u001b[1mINFO    \u001b[0m | \u001b[36mgdsfactory.pdk\u001b[0m:\u001b[36mregister_cells_yaml\u001b[0m:\u001b[36m376\u001b[0m - \u001b[1mRegistered cell 'sample'\u001b[0m\n"
-     ]
-    }
-   ],
+   "outputs": [],
    "source": [
     "import sky130\n",
     "import sky130_hdl21"
@@ -22,7 +14,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "c3e4d92b-c3d3-4677-8416-9c23de62b6c9",
+   "id": "1",
    "metadata": {},
    "outputs": [],
    "source": []
@@ -30,7 +22,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "978298fe-2c3e-492a-b037-28a7ffcbe337",
+   "id": "2",
    "metadata": {},
    "outputs": [],
    "source": []
diff --git a/sky130/hdl21.py b/sky130/hdl21.py
index fa6a0f4da..ac86e500e 100644
--- a/sky130/hdl21.py
+++ b/sky130/hdl21.py
@@ -1,6 +1,7 @@
 """
 Configuration for the hdl21 PDK linking with our source files.
 """
+
 import pathlib
 
 import sky130_hdl21