from microbit import *
while True:
pin8.write_digital(1)
pin11.write_digital(0)
pin12.write_digital(1)
pin16.write_digital(0)
sleep(3000)
pin8.write_digital(0)
pin11.write_digital(1)
pin12.write_digital(0)
pin16.write_digital(1)
sleep(3000)