Where can I find good examples of

from llama_index.llms.openai import OpenAI
from llama_index.core import VectorStoreIndex
from llama_index.core.chat_engine.types import BaseChatEngine
import asyncio


from fastapi import FastAPI, Request, Depends
from fastapi.responses import StreamingResponse

app = FastAPI()

import os

def get_chat_engine() -> BaseChatEngine:
    vector_store_index = VectorStoreIndex.from_documents(documents=[])

    chat_engine = vector_store_index.as_chat_engine(
        chat_mode="context",
        similarity_top_k=10,
        system_prompt="You are a helpful assistant",
    )

    return chat_engine


@app.get("/")
async def root():
    return {"message": "Hello World"}


@app.get("/stream_test")
async def stream_test(
    request: Request,
    chat_engine: BaseChatEngine = Depends(get_chat_engine),
):
    response = await chat_engine.astream_chat("Tell me a poem about raining cats and dogs!")

    # Generate a response.
    async def event_generator():
        async for token in response.async_response_gen():
            if await request.is_disconnected():
                break

            yield token

    return StreamingResponse(event_generator(), media_type="text/plain")


if __name__ == "__main__":
    import uvicorn

    uvicorn.run(
        app,
        loop="asyncio",
        host="0.0.0.0",
        port=8080,
    )