change imports and add fastapi

app.py

@@ -1,7 +1,8 @@
-from langchain.document_loaders import PyPDFLoader
-from langchain.embeddings.openai import OpenAIEmbeddings
+from fastapi import FastAPI
+from langchain_community.document_loaders import PyPDFLoader
+from langchain_community.embeddings import OpenAIEmbeddings
 from langchain.text_splitter import RecursiveCharacterTextSplitter
-from langchain.vectorstores import Chroma
+from langchain_community.vectorstores import Chroma
 from langchain.chains import RetrievalQAWithSourcesChain
 from langchain.chat_models import ChatOpenAI
 from langchain.prompts.chat import (
@@ -16,6 +17,12 @@ from dotenv import load_dotenv
 
 load_dotenv()
 
+app = FastAPI()
+
+@app.get("/")
+async def read_root():
+    return {"Hello": "World"}
+
 text_splitter = RecursiveCharacterTextSplitter(chunk_size=1000, chunk_overlap=100)
 
 system_template = """ Try to find detailed information