add everyting for docs

docs/snippets/modules/model_io/models/chat/get_started.mdx

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+### Setup
+
+To start we'll need to install the OpenAI Python package:
+
+```bash
+pip install openai
+```
+
+Accessing the API requires an API key, which you can get by creating an account and heading [here](https://platform.openai.com/account/api-keys). Once we have a key we'll want to set it as an environment variable by running:
+
+```bash
+export OPENAI_API_KEY="..."
+```
+If you'd prefer not to set an environment variable you can pass the key in directly via the `openai_api_key` named parameter when initiating the OpenAI LLM class:
+
+```python
+from langchain.chat_models import ChatOpenAI
+
+chat = ChatOpenAI(openai_api_key="...")
+```
+
+otherwise you can initialize without any params:
+```python
+from langchain.chat_models import ChatOpenAI
+
+chat = ChatOpenAI()
+```
+
+### Messages
+
+The chat model interface is based around messages rather than raw text.
+The types of messages currently supported in LangChain are `AIMessage`, `HumanMessage`, `SystemMessage`, and `ChatMessage` -- `ChatMessage` takes in an arbitrary role parameter. Most of the time, you'll just be dealing with `HumanMessage`, `AIMessage`, and `SystemMessage`
+
+### `__call__`
+#### Messages in -> message out
+
+You can get chat completions by passing one or more messages to the chat model. The response will be a message.
+
+```python
+from langchain.schema import (
+    AIMessage,
+    HumanMessage,
+    SystemMessage
+)
+
+chat([HumanMessage(content="Translate this sentence from English to French: I love programming.")])
+```
+
+<CodeOutputBlock lang="python">
+
+```
+    AIMessage(content="J'aime programmer.", additional_kwargs={})
+```
+
+</CodeOutputBlock>
+
+OpenAI's chat model supports multiple messages as input. See [here](https://platform.openai.com/docs/guides/chat/chat-vs-completions) for more information. Here is an example of sending a system and user message to the chat model:
+
+
+```python
+messages = [
+    SystemMessage(content="You are a helpful assistant that translates English to French."),
+    HumanMessage(content="I love programming.")
+]
+chat(messages)
+```
+
+<CodeOutputBlock lang="python">
+
+```
+    AIMessage(content="J'aime programmer.", additional_kwargs={})
+```
+
+</CodeOutputBlock>
+
+### `generate`
+#### Batch calls, richer outputs
+
+You can go one step further and generate completions for multiple sets of messages using `generate`. This returns an `LLMResult` with an additional `message` parameter.
+
+```python
+batch_messages = [
+    [
+        SystemMessage(content="You are a helpful assistant that translates English to French."),
+        HumanMessage(content="I love programming.")
+    ],
+    [
+        SystemMessage(content="You are a helpful assistant that translates English to French."),
+        HumanMessage(content="I love artificial intelligence.")
+    ],
+]
+result = chat.generate(batch_messages)
+result
+```
+
+<CodeOutputBlock lang="python">
+
+```
+    LLMResult(generations=[[ChatGeneration(text="J'aime programmer.", generation_info=None, message=AIMessage(content="J'aime programmer.", additional_kwargs={}))], [ChatGeneration(text="J'aime l'intelligence artificielle.", generation_info=None, message=AIMessage(content="J'aime l'intelligence artificielle.", additional_kwargs={}))]], llm_output={'token_usage': {'prompt_tokens': 57, 'completion_tokens': 20, 'total_tokens': 77}})
+```
+
+</CodeOutputBlock>
+
+You can recover things like token usage from this LLMResult
+
+
+```python
+result.llm_output
+```
+
+<CodeOutputBlock lang="python">
+
+```
+    {'token_usage': {'prompt_tokens': 57,
+      'completion_tokens': 20,
+      'total_tokens': 77}}
+```
+
+</CodeOutputBlock>
+

docs/snippets/modules/model_io/models/chat/how_to/chat_model_caching.mdx

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+```python
+import langchain
+from langchain.chat_models import ChatOpenAI
+
+llm = ChatOpenAI()
+```
+
+## In Memory Cache
+
+
+```python
+from langchain.cache import InMemoryCache
+langchain.llm_cache = InMemoryCache()
+
+# The first time, it is not yet in cache, so it should take longer
+llm.predict("Tell me a joke")
+```
+
+<CodeOutputBlock lang="python">
+
+```
+    CPU times: user 35.9 ms, sys: 28.6 ms, total: 64.6 ms
+    Wall time: 4.83 s
+    
+
+    "\n\nWhy couldn't the bicycle stand up by itself? It was...two tired!"
+```
+
+</CodeOutputBlock>
+
+
+```python
+# The second time it is, so it goes faster
+llm.predict("Tell me a joke")
+```
+
+<CodeOutputBlock lang="python">
+
+```
+    CPU times: user 238 µs, sys: 143 µs, total: 381 µs
+    Wall time: 1.76 ms
+
+
+    '\n\nWhy did the chicken cross the road?\n\nTo get to the other side.'
+```
+
+</CodeOutputBlock>
+
+## SQLite Cache
+
+
+```bash
+rm .langchain.db
+```
+
+
+```python
+# We can do the same thing with a SQLite cache
+from langchain.cache import SQLiteCache
+langchain.llm_cache = SQLiteCache(database_path=".langchain.db")
+```
+
+
+```python
+# The first time, it is not yet in cache, so it should take longer
+llm.predict("Tell me a joke")
+```
+
+<CodeOutputBlock lang="python">
+
+```
+    CPU times: user 17 ms, sys: 9.76 ms, total: 26.7 ms
+    Wall time: 825 ms
+
+
+    '\n\nWhy did the chicken cross the road?\n\nTo get to the other side.'
+```
+
+</CodeOutputBlock>
+
+
+```python
+# The second time it is, so it goes faster
+llm.predict("Tell me a joke")
+```
+
+<CodeOutputBlock lang="python">
+
+```
+    CPU times: user 2.46 ms, sys: 1.23 ms, total: 3.7 ms
+    Wall time: 2.67 ms
+
+
+    '\n\nWhy did the chicken cross the road?\n\nTo get to the other side.'
+```
+
+</CodeOutputBlock>

docs/snippets/modules/model_io/models/chat/how_to/llm_chain.mdx

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+```python
+chain = LLMChain(llm=chat, prompt=chat_prompt)
+```
+
+
+```python
+chain.run(input_language="English", output_language="French", text="I love programming.")
+```
+
+<CodeOutputBlock lang="python">
+
+```
+    "J'adore la programmation."
+```
+
+</CodeOutputBlock>

docs/snippets/modules/model_io/models/chat/how_to/prompts.mdx

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+You can make use of templating by using a `MessagePromptTemplate`. You can build a `ChatPromptTemplate` from one or more `MessagePromptTemplates`. You can use `ChatPromptTemplate`'s `format_prompt` -- this returns a `PromptValue`, which you can convert to a string or Message object, depending on whether you want to use the formatted value as input to an llm or chat model.
+
+For convenience, there is a `from_template` method exposed on the template. If you were to use this template, this is what it would look like:
+
+
+```python
+from langchain import PromptTemplate
+from langchain.prompts.chat import (
+    ChatPromptTemplate,
+    SystemMessagePromptTemplate,
+    AIMessagePromptTemplate,
+    HumanMessagePromptTemplate,
+)
+
+template="You are a helpful assistant that translates {input_language} to {output_language}."
+system_message_prompt = SystemMessagePromptTemplate.from_template(template)
+human_template="{text}"
+human_message_prompt = HumanMessagePromptTemplate.from_template(human_template)
+```
+
+
+```python
+chat_prompt = ChatPromptTemplate.from_messages([system_message_prompt, human_message_prompt])
+
+# get a chat completion from the formatted messages
+chat(chat_prompt.format_prompt(input_language="English", output_language="French", text="I love programming.").to_messages())
+```
+
+<CodeOutputBlock lang="python">
+
+```
+    AIMessage(content="J'adore la programmation.", additional_kwargs={})
+```
+
+</CodeOutputBlock>
+
+If you wanted to construct the MessagePromptTemplate more directly, you could create a PromptTemplate outside and then pass it in, eg:
+
+
+```python
+prompt=PromptTemplate(
+    template="You are a helpful assistant that translates {input_language} to {output_language}.",
+    input_variables=["input_language", "output_language"],
+)
+system_message_prompt = SystemMessagePromptTemplate(prompt=prompt)
+```
+

docs/snippets/modules/model_io/models/chat/how_to/streaming.mdx

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+```python
+from langchain.chat_models import ChatOpenAI
+from langchain.schema import (
+    HumanMessage,
+)
+
+
+from langchain.callbacks.streaming_stdout import StreamingStdOutCallbackHandler
+chat = ChatOpenAI(streaming=True, callbacks=[StreamingStdOutCallbackHandler()], temperature=0)
+resp = chat([HumanMessage(content="Write me a song about sparkling water.")])
+```
+
+<CodeOutputBlock lang="python">
+
+```
+    Verse 1:
+    Bubbles rising to the top
+    A refreshing drink that never stops
+    Clear and crisp, it's pure delight
+    A taste that's sure to excite
+    
+    Chorus:
+    Sparkling water, oh so fine
+    A drink that's always on my mind
+    With every sip, I feel alive
+    Sparkling water, you're my vibe
+    
+    Verse 2:
+    No sugar, no calories, just pure bliss
+    A drink that's hard to resist
+    It's the perfect way to quench my thirst
+    A drink that always comes first
+    
+    Chorus:
+    Sparkling water, oh so fine
+    A drink that's always on my mind
+    With every sip, I feel alive
+    Sparkling water, you're my vibe
+    
+    Bridge:
+    From the mountains to the sea
+    Sparkling water, you're the key
+    To a healthy life, a happy soul
+    A drink that makes me feel whole
+    
+    Chorus:
+    Sparkling water, oh so fine
+    A drink that's always on my mind
+    With every sip, I feel alive
+    Sparkling water, you're my vibe
+    
+    Outro:
+    Sparkling water, you're the one
+    A drink that's always so much fun
+    I'll never let you go, my friend
+    Sparkling
+```
+
+</CodeOutputBlock>