from machine import Pin
from utime import sleep

btn = Pin(12, Pin.IN, Pin.PULL_UP)
LedR = Pin(1, Pin.OUT)
LedY = Pin(2, Pin.OUT)
LedG = Pin(4, Pin.OUT)

while True:
    LedR.on()
    sleep(0.1)
    if btn.value() == 0:
        LedR.off()
        LedY.on()
        sleep(1)
        LedY.off()
        LedG.on()
        sleep(2)
        LedG.off()