from machine import Pin 
from time import sleep
 
pins=[15,2,13,4,5,18,19,21,22,23]
length=len(pins)
pins = [Pin(pin, Pin.OUT) for pin in pins]
 
print("it is runnig blinkprogram")
while True:
  for pin_led in pins:
     pin_led.on()
     sleep(0.5)
     pin_led.off()

  for pin_led in reversed(pins):
     pin_led.on()
     sleep(0.5)
     pin_led.off()