Not sure why I keep getting this error to define trip_cost:

```
def hotel_cost(nights):
return 140 * nights
def plane_ride_cost(city):
if city == "Charlotte":
return 183
elif city == "Tampa":
return 220
elif city == "Pittsburgh":
return 222
elif city == "Los Angeles":
return 475
def rental_car_cost(days):
rate = 40
if days >= 7:
total = (rate * days) - 50
return total
elif days >= 3:
total = (rate * days) - 20
return total
else:
total = rate * days
return total
def trip_cost(city, days):
return plane_ride_cost(city) + rental_car_cost(days) + hotel_cost(days - 1)
```