Update app.py

app.py

@@ -54,21 +54,24 @@ class AdvancedPdfChatbot:
     def setup_conversation_chain(self):
         if not self.db:
             raise ValueError("Database not initialized. Please upload a PDF first.")
-            
+        
         refinement_chain = LLMChain(
             llm=self.refinement_llm,
             prompt=self.refinement_prompt
         )
+        
         qa_chain = ConversationalRetrievalChain.from_llm(
             self.llm,
             retriever=self.db.as_retriever(),
             memory=self.memory,
             combine_docs_chain_kwargs={"prompt": self.prompt}
         )
+        
         self.overall_chain = self.CustomChain(refinement_chain=refinement_chain, qa_chain=qa_chain)
 
     class CustomChain(Chain):
         def __init__(self, refinement_chain, qa_chain):
+            """Initialize refinement and QA chains as instance attributes."""
             super().__init__()
             self.refinement_chain = refinement_chain
             self.qa_chain = qa_chain