add everyting for docs

docs/extras/modules/callbacks/token_counting.ipynb

@@ -0,0 +1,84 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "5b0a26fc",
+   "metadata": {},
+   "source": [
+    "# Token counting\n",
+    "LangChain offers a context manager that allows you to count tokens."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "id": "195fd686",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import asyncio\n",
+    "\n",
+    "from langchain.callbacks import get_openai_callback\n",
+    "from langchain.llms import OpenAI\n",
+    "\n",
+    "llm = OpenAI(temperature=0)\n",
+    "with get_openai_callback() as cb:\n",
+    "    llm(\"What is the square root of 4?\")\n",
+    "\n",
+    "total_tokens = cb.total_tokens\n",
+    "assert total_tokens > 0\n",
+    "\n",
+    "with get_openai_callback() as cb:\n",
+    "    llm(\"What is the square root of 4?\")\n",
+    "    llm(\"What is the square root of 4?\")\n",
+    "\n",
+    "assert cb.total_tokens == total_tokens * 2\n",
+    "\n",
+    "# You can kick off concurrent runs from within the context manager\n",
+    "with get_openai_callback() as cb:\n",
+    "    await asyncio.gather(\n",
+    "        *[llm.agenerate([\"What is the square root of 4?\"]) for _ in range(3)]\n",
+    "    )\n",
+    "\n",
+    "assert cb.total_tokens == total_tokens * 3\n",
+    "\n",
+    "# The context manager is concurrency safe\n",
+    "task = asyncio.create_task(llm.agenerate([\"What is the square root of 4?\"]))\n",
+    "with get_openai_callback() as cb:\n",
+    "    await llm.agenerate([\"What is the square root of 4?\"])\n",
+    "\n",
+    "await task\n",
+    "assert cb.total_tokens == total_tokens"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "5e94e0d3",
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "venv",
+   "language": "python",
+   "name": "venv"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.11.3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}