Update app.py

app.py

@@ -4,7 +4,7 @@ from llama_index.llms import Replicate
 from llama_index.embeddings import LangchainEmbedding
 from langchain.embeddings.huggingface import HuggingFaceEmbeddings
 from llama_index import set_global_service_context, ServiceContext, VectorStoreIndex, SimpleDirectoryReader
-
+import os
 # Ensure the environment variable is set
 if "REPLICATE_API_TOKEN" not in os.environ:
     raise ValueError("Please set the REPLICATE_API_TOKEN environment variable.")