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 i in range(len(pins)):
     pins[i].on()
     sleep(0.5)
     pins[i].off()

  for i in range(len(pins)-1,-1,-1):
     pins[i].on()
     sleep(0.5)
     pins[i].off()