from machine import Pin
import time
pins=[9,8,7,6,5,4,3,2,1,0]
def ledshown():
    for i in pins:
        led=Pin(i,Pin.OUT)
        led.value(1)
        time.sleep(0.5)
        led.value(0)
        time.sleep(0.5)
    for i in reversed(pins):
        led=Pin(i,Pin.OUT)
        led.value(1)
        time.sleep(0.5)
        led.value(0)
        time.sleep(0.5)
while True:
    ledshown()