import time
from machine import Pin
led1=Pin(21,Pin.OUT)
led2=Pin(22,Pin.OUT)
led3=Pin(23,Pin.OUT)
buzzer=Pin(18,Pin.OUT)
while True:
    led1.on()
    led2.off()
    led3.off()
    time.sleep(0.5)
    buzzer.on()
    time.sleep(1)
    led1.on()
    led2.on()
    led3.off()
    time.sleep(0.5)
    buzzer.off()
    time.sleep(1)
    led1.on()
    led2.on()
    led3.on()
    time.sleep(0.5)
    buzzer.on()
    time.sleep(1)
    led1.off()
    led2.off()
    led3.off()
    time.sleep(0.5)
    buzzer.off()
    time.sleep(1)