from hcsr04 import HCSR04
from time import sleep
from machine import Pin

sensor = HCSR04(trigger_pin=4,echo_pin=15)
led1= Pin(2,Pin.OUT)
led2= Pin(5,Pin.OUT)
led3= Pin(18,Pin.OUT)

while True:
    distance= sensor.distance_cm()
    print('Distanc:',distance,'cm')
    sleep(0.1)

    if distance<20:
        value(1)
    elif distance<30:
        led1.on()
        led2.on()
    elif distance<40:
        led1.on()
        led2.on()
        led3.on()
    else:
        led1.off()
        led2.off()
        led3.off()