Update app.py

app.py

@@ -21,7 +21,7 @@ def pdf_changes(pdf_doc):
     texts = text_splitter.split_documents(documents)
     db = Chroma.from_documents(texts, embeddings)
     retriever = db.as_retriever()
-    qa = RetrievalQA.from_chain_type(llm=flan_ul2, chain_type="stuff", retriever=retriever, return_source_documents=True)
+    global qa = RetrievalQA.from_chain_type(llm=flan_ul2, chain_type="stuff", retriever=retriever, return_source_documents=True)
     return "Ready"
 
 def infer(question):