from machine import Pin
from time import sleep

red = Pin(2, Pin.OUT)
green = Pin(1, Pin.OUT)
blue = Pin(0, Pin.OUT)

while True:
    blue.off()
    red.on()
    sleep(0.5)
    red.off()
    green.on()
    sleep(0.5)
    green.off()
    blue.on()
    sleep(0.5)