import digitalio
import board
import time
patas = [board.A0, board.A1, board.A2, board.A3]
led = [0] * 4
for k in range (4):
    led[k] = digitalio.DigitalInOut(patas[k])
    led[k].direction = digitalio.Direction.OUTPUT
    led[k].value = False
while True:
    for k in range (3, -1, -1):
        j = k - 1
        if j < 0:
            j = 3
        led[k].value = False
        led[j].value = True
        time.sleep(0.5)