docs: why lcel nit (#18616)

docs/docs/expression_language/why.ipynb

@@ -40,26 +40,7 @@
    "id": "b99b47ec",
    "metadata": {},
    "source": [
-    "%pip install --upgrade --quiet  langchain-core langchain-openai"
+    "%pip install --upgrade --quiet  langchain-core langchain-openai langchain-anthropic"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "id": "dbeac2b8-c441-4d8d-b313-1de0ab9c7e51",
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "from langchain_openai import ChatOpenAI\n",
-    "from langchain_core.prompts import ChatPromptTemplate\n",
-    "from langchain_core.output_parsers import StrOutputParser\n",
-    "\n",
-    "\n",
-    "prompt = ChatPromptTemplate.from_template(\"Tell me a short joke about {topic}\")\n",
-    "model = ChatOpenAI(model=\"gpt-3.5-turbo\")\n",
-    "output_parser = StrOutputParser()\n",
-    "\n",
-    "chain = prompt | model | output_parser"
    ]
   },
   {
@@ -127,6 +108,9 @@
    "metadata": {},
    "outputs": [],
    "source": [
+    "from langchain_openai import ChatOpenAI\n",
+    "from langchain_core.prompts import ChatPromptTemplate\n",
+    "from langchain_core.output_parsers import StrOutputParser\n",
     "from langchain_core.runnables import RunnablePassthrough\n",
     "\n",
     "\n",
@@ -476,7 +460,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from langchain_community.chat_models import ChatAnthropic\n",
+    "from langchain_anthropic import ChatAnthropic\n",
     "\n",
     "anthropic = ChatAnthropic(model=\"claude-2\")\n",
     "anthropic_chain = (\n",
@@ -1010,7 +994,7 @@
    "source": [
     "import os\n",
     "\n",
-    "from langchain_community.chat_models import ChatAnthropic\n",
+    "from langchain_anthropic import ChatAnthropic\n",
     "from langchain_openai import ChatOpenAI\n",
     "from langchain_openai import OpenAI\n",
     "from langchain_core.output_parsers import StrOutputParser\n",
@@ -1070,9 +1054,9 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "poetry-venv",
+   "display_name": "Python 3 (ipykernel)",
    "language": "python",
-   "name": "poetry-venv"
+   "name": "python3"
   },
   "language_info": {
    "codemirror_mode": {