Update app.py

app.py

@@ -336,7 +336,7 @@ def add_certified_user(hf_username, first_name, last_name, pass_percentage):
 
   # Check if this hf_username is already in our dataset:
   check = history.loc[history['hf_username'] == hf_username]
-  if !check.is_empty:
+  if not check.is_empty:
     new_row = pd.DataFrame({'hf_username': hf_username, 'first_name': first_name, 'last_name': last_name, 'pass_percentage': pass_percentage, 'datetime': time.time()})
     print("CHECK", check)
     print("INDEX", check.index[0])