from machine import Pin
import utime
LEDS=[0,5,28,27]
l=[0,0,0,0]
for i in range(4):
    l[i]=Pin(LEDS[i],Pin.OUT)
while True:
    for i in range(4):
        l[i].value(1)
        utime.sleep(0.5)
        l[i].value(0)