update app

app.py

@@ -3,6 +3,7 @@ from llama_index.core import VectorStoreIndex, SimpleDirectoryReader, Settings
 from llama_index.embeddings.huggingface import HuggingFaceEmbedding
 from llama_index.legacy.callbacks import CallbackManager
 from llama_index.llms.openai_like import OpenAILike
+import os
 
 # Create an instance of CallbackManager
 callback_manager = CallbackManager()