Update app.py

def retrieve_context(question, state, k=15)

app.py

@@ -96,7 +96,7 @@ def build_vectorstore(chunks):
     return index, embeddings
 
 
-def retrieve_context(question, state, k=4):
+def retrieve_context(question, state, k=15):
     index = state.get("index")
     chunks = state.get("chunks")