code.py

import time
import RPi.GPIO as GPIO

light_sensor_pin = 5
fan_pin = 6
wheel_pin_numbers = [1, 2, 3, 4]

for pin_number in wheel_pin_numbers:
  GPIO.setup(pin_number, GPIO.OUT)

GPIO.setup(light_sensor_pin, GPIO.IN)

def is_light():
  return GPIO.input(light_sensor_pin)

def foward(stop=False):
  for pin_number in wheel_pin_numbers:
    GPIO.output(pin_number, GPIO.HIGH if not stop else GPIO.LOW)
    
def run_fan(stop=False):
  GPIO.output(fan_pin, GPIO.HIGH if not stop else GPIO.LOW)
  
def go():
  while True:
    if not is_light():
      forward()
    else:
      forward(stop=True)
      break
  
  run_fan()
  time.sleep(2) # amount of seconds to run fan
  run_fan(stop=True)

go()