Update Prompt Template

app.py

@@ -1,6 +1,7 @@
 import time
 import streamlit as st
 from llama_index import ServiceContext, StorageContext, set_global_service_context, VectorStoreIndex, Document
+from llama_index.prompts import PromptTemplate
 from llama_index.embeddings import LangchainEmbedding
 from langchain.embeddings.huggingface import HuggingFaceEmbeddings
 from llama_index.chat_engine.condense_question import CondenseQuestionChatEngine
@@ -77,7 +78,7 @@ def main():
         index = (VectorStoreIndex.from_documents(
             documents, service_context=service_context, storage_context=storage_context, llm=llm))
         # chat_engine = index.as_chat_engine(chat_mode="simple", verbose=True)
-        custom_prompt = ""
+        custom_prompt = PromptTemplate("")
         query_engine = index.as_query_engine()
         chat_engine = CondenseQuestionChatEngine.from_defaults(
             query_engine=query_engine,