from machine import Pin
from time import sleep

leds = [Pin(0, Pin.OUT), Pin(1, Pin.OUT), Pin(2, Pin.OUT), Pin(3, Pin.OUT), 
    Pin(4, Pin.OUT), Pin(5, Pin.OUT)]

pulsanteAvanti = Pin(14, Pin.IN, Pin.PULL_UP)
pulsanteIndietro = Pin(13, Pin.IN, Pin.PULL_UP)

indiceLed = 0

while True:
    if pulsanteAvanti.value() == 0 and indiceLed<len(leds):
        leds[indiceLed].value(1)
        indiceLed += 1
        sleep(0.3)
    
    if pulsanteIndietro.value() == 0 and indiceLed>0:
        indiceLed -= 1
        leds[indiceLed].value(0)
        sleep(0.3)