docs: fix a hub prompt (#3180)

docs/docs/tutorials/plan-and-execute/plan-and-execute.ipynb

@@ -130,36 +130,19 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 7,
+   "execution_count": null,
    "id": "72d233ca-1dbf-4b43-b680-b3bf39e3691f",
    "metadata": {},
-   "outputs": [
-    {
-     "name": "stdout",
-     "output_type": "stream",
-     "text": [
-      "================================\u001b[1m System Message \u001b[0m================================\n",
-      "\n",
-      "You are a helpful assistant.\n",
-      "\n",
-      "=============================\u001b[1m Messages Placeholder \u001b[0m=============================\n",
-      "\n",
-      "\u001b[33;1m\u001b[1;3m{messages}\u001b[0m\n"
-     ]
-    }
-   ],
+   "outputs": [],
    "source": [
     "from langchain import hub\n",
     "from langchain_openai import ChatOpenAI\n",
     "\n",
     "from langgraph.prebuilt import create_react_agent\n",
     "\n",
-    "# Get the prompt to use - you can modify this!\n",
-    "prompt = hub.pull(\"ih/ih-react-agent-executor\")\n",
-    "prompt.pretty_print()\n",
-    "\n",
     "# Choose the LLM that will drive the agent\n",
     "llm = ChatOpenAI(model=\"gpt-4-turbo-preview\")\n",
+    "prompt = \"You are a helpful assistant.\"\n",
     "agent_executor = create_react_agent(llm, tools, state_modifier=prompt)"
    ]
   },
@@ -546,7 +529,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.11.9"
+   "version": "3.12.3"
   }
  },
  "nbformat": 4,