diff --git a/16_reinforcement_learning.ipynb b/16_reinforcement_learning.ipynb
index 15c258e..30f2ab2 100644
--- a/16_reinforcement_learning.ipynb
+++ b/16_reinforcement_learning.ipynb
@@ -574,6 +574,15 @@
     "    plt.show()"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "openai_cart_pole_rendering = False  # don't try, just use the safe way?"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 26,