Update app.py

app.py

@@ -1,11 +1,19 @@
 import os 
 #!pip install -q gradio langchain pypdf chromadb
 import gradio as gr
+from dotenv import load_dotenv
+from PyPDF2 import PdfReader
 from langchain.vectorstores import Chroma
+from langchain.vectorstores import FAISS
 from langchain.document_loaders import PyPDFLoader
 from langchain.text_splitter import CharacterTextSplitter
 from langchain.embeddings import HuggingFaceInferenceAPIEmbeddings
 from langchain.embeddings import HuggingFaceBgeEmbeddings
+from langchain.memory import ConversationBufferMemory
+from langchain.chains import ConversationalRetrievalChain
+from htmlTemplates import css, bot_template, user_template
+from langchain.llms import HuggingFaceHub
+
 
 # Use Hugging Face Inference API embeddings
 inference_api_key = os.environ['HF']