doc updates (#1639)

---------

Co-authored-by: vbarda <vadym@langchain.dev>

examples/code_assistant/langgraph_code_assistant.ipynb

@@ -28,6 +28,16 @@
     "![Screenshot 2024-05-23 at 2.17.42 PM.png](attachment:67b615fe-0c25-4410-9d58-835982547001.png)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "95a34aa2",
+   "metadata": {},
+   "source": [
+    "## Setup\n",
+    "\n",
+    "First, let's install our required packages and set the API keys we will need"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -38,6 +48,39 @@
     "! pip install -U langchain_community langchain-openai langchain-anthropic langchain langgraph bs4"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "602be48f",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import getpass\n",
+    "import os\n",
+    "\n",
+    "\n",
+    "def _set_env(var: str):\n",
+    "    if not os.environ.get(var):\n",
+    "        os.environ[var] = getpass.getpass(f\"{var}: \")\n",
+    "\n",
+    "\n",
+    "_set_env(\"OPENAI_API_KEY\")\n",
+    "_set_env(\"ANTHROPIC_API_KEY\")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "0963fd21",
+   "metadata": {},
+   "source": [
+    "<div class=\"admonition tip\">\n",
+    "    <p class=\"admonition-title\">Set up <a href=\"https://smith.langchain.com\">LangSmith</a> for LangGraph development</p>\n",
+    "    <p style=\"padding-top: 5px;\">\n",
+    "        Sign up for LangSmith to quickly spot issues and improve the performance of your LangGraph projects. LangSmith lets you use trace data to debug, test, and monitor your LLM apps built with LangGraph — read more about how to get started <a href=\"https://docs.smith.langchain.com\">here</a>. \n",
+    "    </p>\n",
+    "</div>    "
+   ]
+  },
   {
    "cell_type": "markdown",
    "id": "38330223-d8c8-4156-82b6-93e63343bc01",