
## Chatbot Recipe:
As the popularity of our Meta Llama 3 models grows, we've seen a surge in demand to adapt them to specific domains, enabling businesses to better serve their customers. For example, a company might have a vast collection of plain text documents related to their custom domain and want to create a chatbot that can answer client questions.

In response to this demand, we're exploring the possibility of building a Llama chatbot that can answer Llama-related questions using our Meta Llama 3 models. In this tutorial, we'll demonstrate how to do just that. While our Meta Llama 3 70B Instruct model is an excellent candidate, its production costs are relatively high. To reduce these costs, we'll focus on creating a Llama chatbot based on the Meta Llama 8B Instruct model, aiming to achieve similar accuracy while minimizing inference costs.

One common approach to produce a model based on new domain data is **fine-tuning**. The idea is to start from a pre-trained model that already has some knowledge of language from its pre-training and adapt it to a new domain. However, [recent paper](https://arxiv.org/pdf/2405.05904) highlights the risk of using supervised fine-tuning to update LLMs' knowledge, as it presents empirical evidence that acquiring new knowledge through fine-tuning is correlated with hallucinations w.r.t. preexisting knowledge. Fine-tuning can also be costly if the domain knowledge has to be updated frequently.

Another solution is to use **RAG (Retrieval-Augmented Generation)**, which combines the strengths of traditional information retrieval systems (such as databases) with the capabilities of generative large language models (LLMs). RAG operates by first retrieving relevant information from a database using a query generated by the LLM. This retrieved information is then integrated into the LLM's query input, enabling it to generate more accurate and contextually relevant text. This helps to reduce LLM hallucination as the related documents are provided to LLM and has a lower cost to update the domain knowledge.

In this tutorial, we'll use **Retrieval Augmented Fine Tuning (RAFT)**, a technique that combines fine-tuning with RAG to better utilize custom domain text data. RAFT is a general recipe for fine-tuning a pre-trained Large Language Model (LLM) to a domain-specific RAG setting. It helps LLM to better utilize custom domain text data, by ignoring those documents that don’t help in answering the question. This approach can create a more factual model and reduce LLM hallucinations during inference.

The process involves preparing training data with each data point containing:

* A question (Q)
* A set of documents (D)
* A corresponding Chain-of-thought style answer (A*) generated from one of the documents (D*)

RAFT tries to teach the models to differentiate between two types of documents:

* Oracle documents (D*): documents from which the answer to the question can be deduced
* Distractor documents (Di): documents that do not contain answer-relevant information

The following graph illustrates the RAFT main concepts:
![RAFT images](images/RAFT.png)

For more information on RAFT, please refer to their [blog post](https://gorilla.cs.berkeley.edu/blogs/9_raft.html).

## Fine-tuning Llama

To build a Llama bot, we need to collect relevant text data. Ideally, we would include a vast range of Llama-related web documents, but for demo purposes, we'll focus on official documents. For example, we can use the raw text from official web pages listed in [Getting started with Meta Llama](https://llama.meta.com/get-started/), excluding the FAQ page since some evaluation questions will come from there.

We have two options to obtain the text data: using a local folder or web crawling. For the local folder option, we can download the desired documents in PDF, Text, or Markdown format to the "data" folder specified in the [raft.yaml](./raft.yaml) file. Langchain DirectoryLoader will load files in that folder, but it may also ask us to install more package dependency if the files formats are not supported natively.

Alternatively, we can create a sitemap XML file, similar to the example below, and put the file path in the [raft.yaml](./raft.yaml) file, so eventually a Langchain SitemapLoader can retrieve all the text from the web pages.

```xml
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url>
    <loc>http://llama.meta.com/responsible-use-guide/</loc>
  </url>
  <!-- more URLs -->
</urlset>
```

## Create RAFT Dataset

To create a RAFT dataset from the prepared documents, we can use the Meta Llama 3 70B Instruct model either through APIs from LLM cloud providers or by hosting a local VLLM server.

For this example, we'll demonstrate how to create a VLLM OpenAI-compatible server that hosts Meta Llama 3 70B Instruct locally and generates the RAFT dataset.

**Local Server Setup**

First, ensure VLLM is installed. Then, run the following command to start the VLLM server:
```bash
CUDA_VISIBLE_DEVICES=0,1 python -m vllm.entrypoints.openai.api_server  --model meta-Llama/Meta-Llama-3-70B-Instruct --tensor-parallel-size 2 --disable-log-requests --port 8001
```
**Note**: Make sure the port is available, and the server requires at least 135GB GPU memory, so we need to use multiple GPUs in a tensor parallel way.

**Querying the Server**

Once the server is ready, query it using the following command in another terminal:
```bash
python raft.py -u "http://localhost:8001/v1" -k "EMPTY" -t 4
```
If you prefer to use a cloud API, replace the endpoint URL with the cloud provider's URL and set the API key using the `-k` flag or environment variables.

**RAFT Dataset Generation**

The [raft.py](raft.py) script reads all documents from local or web sources, depending on the settings, and splits the data into text chunks of 1000 characters using RecursiveCharacterTextSplitter.

Then, it applies the `question_prompt_template` defined in [raft.yaml](raft.yaml) to each chunk to generate queries to Meta Llama 3 70B model, and the model will generate a question list (By default 4 questions in that list) for each text chunk. For each question and corresponding text chunk, we generate a Chain-of-Thought (COT) style answer using Meta Llama 3 70B Instruct APIs.

Once we have the COT answers, we can create a dataset where each sample contains an "instruction" section. This section includes some unrelated chunks called distractors (by default, we add 4 distractors). In the original RAFT method, there is an oracle probability P (by default, 80%) that a related document will be included. This means that there is a 1-P (by default, 20%) chance that no related documents are provided, and the RAFT model should still try to predict the COT answer label, as stated in the blog, "By removing the oracle documents in some instances of the training data, we are compelling the model to memorize domain-knowledge."

**Modification to Add Refusal Examples**

In this tutorial, we made an important modification by adding additional refusal examples (by default, this refusal probability is 5%). When the related documents are not presented, we set the COT answer label to "Sorry, I don't know the answer to this question because related documents are not found. Please try again." Our hypothesis is that this will increase answer precision and reduce chatbot hallucination. In real-world production scenarios, we prefer that the chatbot refuses to answer when not enough context is provided, so that we can detect this refusal signal and mitigate the risk of producing wrong or misleading answers (e.g., we can ask a human agent to take over the conversation to better serve customers).

**RAFT Format JSON Example**

Here is a RAFT format JSON example from our saved `raft.jsonl` file:
```json
{
   "id":"seed_task_228",
   "type":"general",
   "question":"What is the context length supported by Llama 3 models?",
   "context":{
      "sentences":[
         [
            "DISTRACT_DOCS 1"
            "DISTRACT_DOCS 2"
            "We hope that Code Llama will inspire others to leverage Llama 2 to create new innovative tools for research and commercial products. Download the model Explore more on Code Llama Discover more about Code Llama here \u2014 visit our resources, ranging from our research paper, getting started guide and more. Code Llama GitHub repository Research paper Download the model Getting started guide Meta Llama 3 Build the future of AI with Meta Llama 3 Now available with both 8B and 70B pretrained and instruction-tuned versions to support a wide range of applications Build the future of AI with Meta Llama 3 Now available with both 8B and 70B pretrained and instruction-tuned versions to support a wide range of applications Get Started Experience Llama 3 on Meta AI Experience Llama 3 with Meta AI We\u2019ve integrated Llama 3 into Meta AI, our intelligent assistant, that expands the ways people can get things done, create and connect with Meta AI. You can see first-hand the performance of Llama 3 by using Meta AI for coding tasks and problem solving. Whether you're developing agents, or other AI-powered applications, Llama 3 in both 8B and 70B will offer the capabilities and flexibility you need to develop your ideas. Experience Llama 3 on Meta AI Enhanced performance Experience the state-of-the-art performance of Llama 3, an openly accessible model that excels at language nuances, contextual understanding, and complex tasks like translation and dialogue generation. With enhanced scalability and performance, Llama 3 can handle  multi-step tasks effortlessly, while our refined post-training processes significantly lower false refusal rates, improve response alignment, and boost diversity in model answers. Additionally, it drastically elevates capabilities like reasoning, code generation, and instruction following. Build the future of AI with Llama 3. Download Llama 3 Getting Started Guide With each Meta Llama request, you will receive: Meta Llama Guard 2 Getting started guide Responsible Use Guide Acceptable use policy Model card Community license agreement Benchmarks Llama 3 models take data and scale to new heights. It\u2019s been trained on our two recently announced custom-built 24K GPU clusters on over 15T token of data \u2013 a training dataset 7x larger than that used for Llama 2, including 4x more code. This results in the most capable Llama model yet, which supports a 8K context length that doubles the capacity of Llama 2. Model card Trust & safety A comprehensive approach to responsibility With the release of Llama 3, we\u2019ve updated the Responsible Use Guide (RUG) to provide the most comprehensive information on responsible development with LLMs. Our system-centric approach includes updates to our trust and safety tools with Llama Guard 2, optimized to support the newly announced taxonomy published by MLCommons expanding its coverage to a more comprehensive set of safety categories, Code Shield, and Cybersec Eval 2. In line with the principles outlined in our RUG , we recommend thorough checking and filtering of all inputs to and outputs from LLMs based on your unique content guidelines for your intended use case and audience. Meta Llama Guard 2 Explore more on Meta Llama 3 Introducing Meta Llama 3: The most capable openly available LLM to date Read the blog Meet Your New Assistant: Meta AI, Built With Llama 3 Learn more Meta Llama 3 repository View repository Model card Explore Meta Llama 3 License META LLAMA 3 COMMUNITY LICENSE AGREEMENT Meta Llama 3 Version Release Date: April 18, 2024 \u201c Agreement \u201d means the terms and conditions for use, reproduction, distribution and modification of the Llama Materials set forth herein. \u201c Documentation \u201d means the specifications, manuals and documentation accompanying Meta Llama 3 distributed by Meta at https:\/\/llama.meta.com\/get-started\/ .",
            "DISTRACT_DOCS 3"
            "DISTRACT_DOCS 4"
         ]
      ],
      "title":[
         [
            "placeholder_title",
            "placeholder_title",
            "placeholder_title",
            "placeholder_title",
            "placeholder_title",
         ]
      ]
   },
   "oracle_context":"We hope that Code Llama will inspire others to leverage Llama 2 to create new innovative tools for research and commercial products. Download the model Explore more on Code Llama Discover more about Code Llama here \u2014 visit our resources, ranging from our research paper, getting started guide and more. Code Llama GitHub repository Research paper Download the model Getting started guide Meta Llama 3 Build the future of AI with Meta Llama 3 Now available with both 8B and 70B pretrained and instruction-tuned versions to support a wide range of applications Build the future of AI with Meta Llama 3 Now available with both 8B and 70B pretrained and instruction-tuned versions to support a wide range of applications Get Started Experience Llama 3 on Meta AI Experience Llama 3 with Meta AI We\u2019ve integrated Llama 3 into Meta AI, our intelligent assistant, that expands the ways people can get things done, create and connect with Meta AI. You can see first-hand the performance of Llama 3 by using Meta AI for coding tasks and problem solving. Whether you're developing agents, or other AI-powered applications, Llama 3 in both 8B and 70B will offer the capabilities and flexibility you need to develop your ideas. Experience Llama 3 on Meta AI Enhanced performance Experience the state-of-the-art performance of Llama 3, an openly accessible model that excels at language nuances, contextual understanding, and complex tasks like translation and dialogue generation. With enhanced scalability and performance, Llama 3 can handle  multi-step tasks effortlessly, while our refined post-training processes significantly lower false refusal rates, improve response alignment, and boost diversity in model answers. Additionally, it drastically elevates capabilities like reasoning, code generation, and instruction following. Build the future of AI with Llama 3. Download Llama 3 Getting Started Guide With each Meta Llama request, you will receive: Meta Llama Guard 2 Getting started guide Responsible Use Guide Acceptable use policy Model card Community license agreement Benchmarks Llama 3 models take data and scale to new heights. It\u2019s been trained on our two recently announced custom-built 24K GPU clusters on over 15T token of data \u2013 a training dataset 7x larger than that used for Llama 2, including 4x more code. This results in the most capable Llama model yet, which supports a 8K context length that doubles the capacity of Llama 2. Model card Trust & safety A comprehensive approach to responsibility With the release of Llama 3, we\u2019ve updated the Responsible Use Guide (RUG) to provide the most comprehensive information on responsible development with LLMs. Our system-centric approach includes updates to our trust and safety tools with Llama Guard 2, optimized to support the newly announced taxonomy published by MLCommons expanding its coverage to a more comprehensive set of safety categories, Code Shield, and Cybersec Eval 2. In line with the principles outlined in our RUG , we recommend thorough checking and filtering of all inputs to and outputs from LLMs based on your unique content guidelines for your intended use case and audience. Meta Llama Guard 2 Explore more on Meta Llama 3 Introducing Meta Llama 3: The most capable openly available LLM to date Read the blog Meet Your New Assistant: Meta AI, Built With Llama 3 Learn more Meta Llama 3 repository View repository Model card Explore Meta Llama 3 License META LLAMA 3 COMMUNITY LICENSE AGREEMENT Meta Llama 3 Version Release Date: April 18, 2024 \u201c Agreement \u201d means the terms and conditions for use, reproduction, distribution and modification of the Llama Materials set forth herein. \u201c Documentation \u201d means the specifications, manuals and documentation accompanying Meta Llama 3 distributed by Meta at https:\/\/llama.meta.com\/get-started\/ .",
   "cot_answer":"Here's the step-by-step reasoning to answer the question:\n\n1. The question asks about the context length supported by Llama 3 models.\n2. In the context, we need to find the relevant information about Llama 3 models and their context length.\n3. The relevant sentence is: \"This results in the most capable Llama model yet, which supports a 8K context length that doubles the capacity of Llama 2.\"\n##begin_quote## This results in the most capable Llama model yet, which supports a 8K context length that doubles the capacity of Llama 2. ##end_quote##\n4. From this sentence, we can see that Llama 3 models support a context length of 8K.\n\n<ANSWER>: 8K",
   "instruction":"<DOCUMENT> DISTRACT_DOCS 1 <\/DOCUMENT>...<DOCUMENT> DISTRACT_DOCS 4 <\/DOCUMENT>\nWhat is the context length supported by Llama 3 models?"
}
```
As shown in the above example, we have a "question" section for the generated question, a "cot_answer" section for the generated COT answers (where the final answer will be added after the "<ANSWER>" token), and an "instruction" section that has all the documents included (each document split by `<DOCUMENT>` and `</DOCUMENT>` tags) and finally the generated question appended at the end. This "instruction" section will be the input during fine-tuning, and the "cot_answer" will be the output label that the loss will be calculated on.

## Creating an Evaluation Set
To create a reliable evaluation set, it's ideal to use human-annotated question and answer pairs. This ensures that the questions are relevant and the answers are accurate. However, human annotation is time-consuming and costly. For demonstration purposes, we'll use a subset of the validation set, which will never be used in the fine-tuning. We only need to keep the "question" section and the final answer section, marked by the `<ANSWER>` tag in "cot_answer". We'll manually check each example and select only the good ones. We want to ensure that the questions are general enough to be used for web search engine queries and are related to Llama. We'll also use some QA pairs from our FAQ page, with modifications. This will result in 72 question and answer pairs as our evaluation set, saved as `eval_llama.json`.

## Fine-Tuning Steps
Once the RAFT dataset is ready in JSON format, we can start fine-tuning. Unfortunately, the LORA method didn't produce good results, so we'll use the full fine-tuning method. We can use the following commands as an example in the llama-cookbook main folder:

```bash
export PATH_TO_ROOT_FOLDER=./raft-8b
export PATH_TO_RAFT_JSON=recipes/use_cases/end2end-recipes/raft/output/raft.jsonl
torchrun --nnodes 1 --nproc_per_node 4  recipes/quickstart/finetuning/finetuning.py --enable_fsdp --lr 1e-5 --context_length 8192 --num_epochs 1 --batch_size_training 1 --model_name meta-Llama/Meta-Llama-3-8B-Instruct --dist_checkpoint_root_folder $PATH_TO_ROOT_FOLDER --dist_checkpoint_folder fine-tuned  --use_fast_kernels --dataset "custom_dataset" --custom_dataset.test_split "test" --custom_dataset.file "recipes/finetuning/datasets/raft_dataset.py" --use-wandb  --run_validation True  --custom_dataset.data_path $PATH_TO_RAFT_JSON
```

For more details on multi-GPU fine-tuning, please refer to the [multigpu_finetuning.md](../../getting-started/finetuning/multigpu_finetuning.md) in the finetuning recipe.

Next, we need to convert the FSDP checkpoint to a HuggingFace checkpoint using the following command:

```bash
python src/llama_cookbook/inference/checkpoint_converter_fsdp_hf.py --fsdp_checkpoint_path  "$PATH_TO_ROOT_FOLDER/fine-tuned-meta-Llama/Meta-Llama-3-8B-Instruct" --consolidated_model_path "$PATH_TO_ROOT_FOLDER"
```

For more details on FSDP to HuggingFace checkpoint conversion, please refer to the [readme](../../getting-started/finetuning/multigpu_finetuning.md) in the inference/local_inference recipe.

## Evaluation Steps
Once we have the RAFT model, we need to evaluate its performance. In this tutorial, we'll not only use traditional evaluation methods (e.g., calculating exact match rate or ROUGE score) but also use LLM as a judge to score model-generated answers.

We'll launch a VLLM server to host our converted model from `PATH_TO_ROOT_FOLDER`. To make things easier, we can rename the model folder to `raft-8b`.

```bash
CUDA_VISIBLE_DEVICES=1 python -m vllm.entrypoints.openai.api_server  --model raft-8b --port 8000  --disable-log-requests
```

Similarly, if we want to get the 8B instruct baseline, we can launch a 8B model VLLM server instead:

```bash
CUDA_VISIBLE_DEVICES=1 python -m vllm.entrypoints.openai.api_server  --model  meta-Llama/Meta-Llama-3-8B-Instruct --port 8000  --disable-log-requests
```

On another terminal, we can use another Meta Llama 3 70B Instruct model as a judge to compare the answers from the RAFT 8B model with the ground truth and get a score. To do this, we need to host another Meta Llama 3 70B Instruct VLLM server locally with the command, making sure the port is not in use:
```bash
CUDA_VISIBLE_DEVICES=2,3 python -m vllm.entrypoints.openai.api_server  --model meta-Llama/Meta-Llama-3-70B-Instruct --tensor-parallel-size 2 --disable-log-requests --port 8001
```

Then, we can pass the ports to the eval script to evaluate our RAFT model once our `raft-8b` VLLM server is running:
```bash
CUDA_VISIBLE_DEVICES=4 python raft_eval.py -m raft-8b -u "http://localhost:8000/v1" -j "http://localhost:8001/v1" -r 5
```

To evaluate the 8B baseline, we can use the following command once our 8B VLLM server is running:
```bash
CUDA_VISIBLE_DEVICES=4 python raft_eval.py -m meta-Llama/Meta-Llama-3-8B-Instruct -u "http://localhost:8000/v1" -j "http://localhost:8001/v1" -r 5
```

**NOTE**: Please ensure that the `--model` in VLLM server creation matches the `--m` in raft_eval.py. Otherwise, VLLM will raise a `model not found` error. By default, the RAFT model is called "raft-8b". Here, `-u` specifies the RAFT model endpoint URL, `-j` specifies the judge model endpoint URL, and `-r` defines how many top-k documents the RAG should retrieve.

This [raft_eval.py](./raft_eval.py) script will load questions from the evaluation set, generate answers from models and models+RAG, and compare the generated answers with the ground truth to get the evaluation metrics, such as ROUGE score or LLM-as-judge score. It will then save those metrics and evaluation details to eval logs.

## Experiment Results

**Overview**

During our experiments, we encountered issues with using only the Llama website data, which consisted 1980+ RAFT examples generated from 327K characters text. We believed that this initial data was insufficient, so we created an additional PyTorch RAFT dataset using text from official [Pytorch blogs](https://pytorch.org/blog/) and [Pytorch tutorials](https://pytorch.org/tutorials/). This new dataset contains 20K+ RAFT examples generated from 4.7 million characters. We combined both datasets to create an `all_data` dataset. We then fine-tuned the 8B model on each dataset separately for 1 epoch with a learning rate of 1e-5, resulting in three RAFT models: `llama_only`, `pytorch_only`, and `all_data`.

**Evaluation on non-RAG baseline**

First we run a non-RAG baseline, just using Meta Llama 3 8B Instruct and Meta Llama 3 70B Instruct model to see if our model can already answers some questions without any fine-tuning and external knowledge base. The LLM score, the percentage of correctness marked by LLM_as_judge, for 8B is 47.9% and 70B is 59.2%. Clearly, there are some information that has been pretrained into our Meta Llama 3 models.

**Evaluation on RAG baseline**

Then we tested these 3 RAFT models with Langchain RAG, along with the Meta Llama 3 8B Instruct and Meta Llama 3 70B Instruct RAG baselines, using the RAG document top-k retrieve parameters of 3, 5, and 7. We deployed a Meta Llama 70B Instruct model as the judge to score our model-generated answers against the ground truth in our evaluation set. The LLM scores are shown below:


![RAFT LLM_score comparison](images/LLM_score_comparison.png)

Our results showed that RAFT models performed similarly to the 8B RAG baseline, but noticeably worse than the 70B RAG baseline when context documents were limited (top_k <= 5). However, when top_k = 7, the RAFT models performance suddenly increase, with the `all_data` 8B model achieving a score of 76.06% which beats the 70B baseline's 74.65%.

**Refusal Examples**

We also analyzed the number of refusal examples, where the model responded with "Sorry, I do not know." The `all_data` model was more cautious and tended to refuse to answer, whereas the `llama_only` RAFT model did not learn to refuse at all, likely due to the limited dataset size.

![Num of refusal comparison](images/Num_of_refusal_comparison.png)

**Precision Analysis**

We calculated the precision of our model answers, which represents the likelihood of producing correct answers when the model decides to respond. The formula used was $\frac{LLMScore}{1-\frac{numRefusal}{totalQA}}$.

![Answers Precision](images/Answers_Precision.png)

Note that the 8B and 70B RAG baselines never refused to answer, so their precision was equivalent to their LLM_score. Our `all_data` and `pytorch_only` models tended to refuse to answer when provided documents were limited (top_k < 5), but when they did generate an answer, the likelihood of it being correct was higher. Specifically, when top_k = 7, the `all_data` RAFT model had an 82.97% likelihood of producing a correct answer when it decided to respond, outperforming the 70B baseline.

**Example Comparisons**

Here are some examples where our `all_data` RAFT model correctly answered questions that the 70B baseline failed to answer:

```
Comparing interested question: What tokenizer is used as the basis for the special tokens in Meta Llama
ground_truth:  tiktoken
True all_data_RAG_answers: <ANSWER>: The tokenizer used as the basis for the special tokens in Meta Llama is tiktoken.
False 70B_RAG_answers: <ANSWER>: The tokenizer used as the basis for the special tokens in Meta Llama is SentencePiece.
```

```
Comparing interested question: What is the license under which the Llama Guard model and its weights are released?
groud_truth:  The license is the same as Llama 3, which can be found in the LICENSE file and is accompanied by the Acceptable Use Policy.
True all_data_RAG_answers: <ANSWER>: The license under which the Llama Guard model and its weights are released is the same as Llama 3, and the [LICENSE](../LICENSE) file contains more information about the license.
False 70B_RAG_answers: <ANSWER>: The Llama Guard model and its weights are licensed under the Llama 2 Community license.
```

**Key Takeaways**

From our experiments, we learned:

1. Few thousand RAFT examples are insufficient, and at least 10K examples are recommended.
2. The LLM_as_judge is not always reliable, and we noticed there are chances that answers were scored incorrectly.
3. The chunk_size for RAFT documents and RAG documents should be the same.
4. The RAFT method appears to help the LLM differentiate related documents from distractors rather than forcing it to memorize the training data, as we used Pytorch data as additional data to help our Llama chatbot to answer Llama questions. More research experiments will be needed to understand more about this.

## Local Inference Steps

Once we evaluated and refined our RAFT model, we can deploy it locally to interact with it by asking questions manually. To do this, run the following command:

```bash
python recipes/inference/local_inference/inference.py --model_name raft-8b
```

For more details,please check [local_inference recipe](../../getting-started/inference/local_inference/README.md)

## Acknowledgement

Finally, we would like to extend special thanks to Tianjun Zhang, the first author of the [RAFT paper](https://arxiv.org/pdf/2403.10131), for collaborating with us on this tutorial and providing valuable guidance throughout our experiments. Our code is also partially inspired by the [RAFT section in Gorilla github](https://github.com/ShishirPatil/gorilla/tree/main/raft).
