Update app.py

app.py

@@ -187,7 +187,7 @@ ask = col2.button("Ask")
 
 if ask:
 
-    if api_key is "":
+    if (choice=="openai" and os.environ["OPENAI_API_KEY"]=="") or (choice=="togethercomputer/GPT-NeoXT-Chat-Base-20B" and os.environ["HUGGINGFACEHUB_API_TOKEN"]==""):
         st.write(f"**{BOOK_NAME}:** Whoops looks like you forgot your API key buddy")
         st.stop()
     else: