from machine import Pin 
import utime 

led_1= Pin ( 4, Pin.OUT)
led_2= Pin ( 10, Pin.OUT)
led_3= Pin ( 4, Pin.OUT)

while True :
    led_1.value (1)
    utime.sleep (1)
    led_1.value (0)
    utime.sleep (1)

    led_2.value (1)
    utime.sleep (1)
    led_2.value (0)
    utime.sleep (1)

    led_3.value (1)
    utime.sleep (1)
    led_3.value (0)
    utime.sleep (1)