from machine import Pin
from time import sleep

while True:
    for j in range(1,7,1):
        led = Pin(j,Pin.OUT)
        led.value(1)
        sleep(0.5)
        led.value(0)
    for j in range(5,1,-1):
        led = Pin(j,Pin.OUT)
        led.value(1)
        sleep(0.5)
        led.value(0)