from machine import Pin
import time
r1 = Pin(21,Pin.OUT)
r2 = Pin(22,Pin.OUT)
r3 = Pin(23,Pin.OUT)
bzr = Pin(18,Pin.OUT)
while True:
    if:
    r1.on()
    r2.off()
    r3.off()
    bzr.value()==1
     time.sleep(0.5)
    elif
    r1.on()
    r2.on()
    r3.off()
    bzr.value()==0
    time.sleep(0.5)
    elif
    r1.on()
    r2.on()
    r3.on()
    bzr.value()==1
    time.sleep(0.5)
    elif
    r1.off()
    r2.off()
    r3.off()
    bzr.value()==0
    time.sleep(0.5)