Update app.py

app.py

@@ -12,6 +12,7 @@ from langchain_community.document_loaders import PyPDFLoader
 from langchain_openai import ChatOpenAI
 from langchain.callbacks import get_openai_callback
 from io import BytesIO
+from langchain.chains.combine_documents import create_stuff_documents_chain
 
 openai.api_key = os.getenv("OPENAI_API_KEY")
 
@@ -39,7 +40,7 @@ def summarize_document(docs, llm):
 
     {context}
     """
-    chain = RetrievalQA.from_chain_type(llm=llm, chain_type="stuff", retriever=None)
+    chain = create_stuff_documents_chain(llm, prompt)
     with get_openai_callback() as cb:  
       summary = chain.invoke({"context": docs})
     return summary, cb