Cark Park Occupancy

def validate_parking(parking):
    parking = parking.strip()
    try:
        if parking.startswith('[') and parking.endswith(']'):
            parking = parking[1:-1]
        parking = [int(slot) for slot in parking.split(',')]
        if parking and all(slot in [0, 1] for slot in parking):
            return parking
    except ValueError:
        return None

def calculate_occupancy(parking):
    slots = len(parking)
    spaces = parking.count(0)
    filled = slots - spaces
    occupied_percentage = int(round(filled / slots * 100))
    return slots, filled, spaces, occupied_percentage

def report(car_parks):
    print('Car park occupancy levels\n')
    print("Park| Slots| Occpd| Vacant| % occupied ")
    print("----|------|------|-------|-------------")
    for park, car_park in enumerate(car_parks, start=1):
        parking = validate_parking(car_park)
        if parking:
            slots, filled, spaces, occupied_percentage = calculate_occupancy(parking)
            print(f'{park:3} | {slots:4} | {filled:4} | {spaces:4}  | '
                  f'{occupied_percentage:3}%')
        else:
            print(f'{park:3} | invalid data: {car_park.strip()}')

def car_parks_occupancy(filename):
    try:
        car_parks = open(filename).readlines()
    except IOError:
        print(f'Unable to open data file{filename}')
    else:
        report(car_parks)

car_parks_occupancy('car_parks.csv')