diff --git a/03_classification.ipynb b/03_classification.ipynb
index e2314b1..b574513 100644
--- a/03_classification.ipynb
+++ b/03_classification.ipynb
@@ -852,6 +852,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
+    "# since sklearn 0.22, you can use sklearn.metrics.plot_confusion_matrix()\n",
     "def plot_confusion_matrix(matrix):\n",
     "    \"\"\"If you prefer color and a colorbar\"\"\"\n",
     "    fig = plt.figure(figsize=(8,8))\n",