fix users bug and emphasize kernal restart (#2407)

Author: TheMichaelHu

tables/automl/notebooks/music_recommendation/music_recommendation.ipynb

@@ -84,14 +84,14 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "! pip install --upgrade --quiet google-cloud-automl google-cloud-bigquery"
+    "! pip3 install --upgrade --quiet google-cloud-automl google-cloud-bigquery"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Restart the kernel to allow `automl_v1beta1` to be imported. The following cell should succeed after a kernel restart:"
+    "__Restart the kernel__ to allow `automl_v1beta1` to be imported. The following cell should succeed after a kernel restart:"
    ]
   },
   {
@@ -624,10 +624,10 @@
     "    WHERE user = \"{}\" AND CAST(tables.value AS INT64) = 1\n",
     "    ORDER BY score DESC\n",
     "    LIMIT {}\n",
-    "\"\"\".format(output_uri[5:].replace(\":\", \".\"), training_table, user, n)\n",
+    "\"\"\".format(output_uri[5:].replace(\":\", \".\"), training_table, users[0], n)\n",
     "query_job = bq_client.query(query)\n",
     "\n",
-    "print(\"Top {} song recommended for {}:\".format(n, user))\n",
+    "print(\"Top {} song recommended for {}:\".format(n, users[0]))\n",
     "for idx, row in enumerate(query_job):\n",
     "    print(\"{}.\".format(idx + 1), row[\"song\"])"
    ]