Update app.py

app.py

@@ -16,6 +16,8 @@ from langchain_community.vectorstores import FAISS
 from langchain_community.llms import HuggingFaceHub
 from langchain_core.prompts import PromptTemplate
 from langchain.chains import RetrievalQA
+import os 
+
 
 # Disclaimer to be dispalyed at the bottom of each tab
 disclaimer = """