Wfh/ref links (#8454)

docs/extras/modules/chains/how_to/custom_chain.ipynb

@@ -15,10 +15,7 @@
    "execution_count": 11,
    "id": "c19c736e-ca74-4726-bb77-0a849bcc2960",
    "metadata": {
-    "tags": [],
-    "vscode": {
-     "languageId": "python"
-    }
+    "tags": []
    },
    "outputs": [],
    "source": [
@@ -28,7 +25,7 @@
     "\n",
     "from pydantic import Extra\n",
     "\n",
-    "from langchain.schema import BaseLanguageModel\n",
+    "from langchain.schema.language_model import BaseLanguageModel\n",
     "from langchain.callbacks.manager import (\n",
     "    AsyncCallbackManagerForChainRun,\n",
     "    CallbackManagerForChainRun,\n",
@@ -130,11 +127,7 @@
    "cell_type": "code",
    "execution_count": 12,
    "id": "18361f89",
-   "metadata": {
-    "vscode": {
-     "languageId": "python"
-    }
-   },
+   "metadata": {},
    "outputs": [
     {
      "name": "stdout",