Update app.py

app.py

@@ -228,10 +228,11 @@ def get_possible_destinations():
 
 def get_dataframe_of(day):
     global cities_datafram, today_dataframe, tomorrow_dataframe
+    today_df, tomorrow_df = today_dataframe, tomorrow_dataframe
     if   (day.lower() == 'today'):
-        return today_dataframe
+        return today_df
     elif (day.lower() == 'tomorrow'):
-        return tomorrow_dataframe
+        return tomorrow_df
 
 def get_specific_flights(day, max_delay, departure_hour, ampm, weather, destinations, yes):
     df = get_dataframe_of(day)