Update app.py

app.py

@@ -22,6 +22,12 @@ from langchain import hub
 import pickle
 import os
 from langchain_community.retrievers import PineconeHybridSearchRetriever
+from langchain.chains import create_history_aware_retriever, create_retrieval_chain
+from langchain.chains.combine_documents import create_stuff_documents_chain
+from langchain_community.chat_message_histories import ChatMessageHistory
+from langchain_core.chat_history import BaseChatMessageHistory
+from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder
+from langchain_core.runnables.history import RunnableWithMessageHistory
 
 
 # Load environment variables