Update app.py

app.py

@@ -3,7 +3,9 @@ from langchain_core.vectorstores import InMemoryVectorStore
 from langchain.chains import RetrievalQA
 from langchain_community.embeddings import HuggingFaceEmbeddings
 from langchain_groq import ChatGroq
-
+from langchain_core.prompts import ChatPromptTemplate
+from langchain.chains import create_retrieval_chain
+from langchain.chains.combine_documents import create_stuff_documents_chain
 
 """
 For more information on `huggingface_hub` Inference API support, please check the docs: https://huggingface.co/docs/huggingface_hub/v0.22.2/en/guides/inference