When doing this problem, I came across this question: does the order of arguments taken in functions matter? Because apparently my code below results into an error: "cannot concatenate 'str' and 'NoneType' objects".
def trip_cost(days,city,spending_money): return hotel_cost(days) + plane_ride_cost(city) + rental_car_cost(days) + spending_money
If I switch "days" and "city" it would work. Could someone explain this?