#QUESTION 3
from machine import Pin, Timer
LED0 = Pin(21, Pin.OUT)
LED1 = Pin(19, Pin.OUT)
LED2 = Pin(18, Pin.OUT)
LED4 = Pin(5, Pin.OUT)
i = 0

def binarycount(x):
    binary ='{0:04b}'.format(x)
    LED0.value(int(binary[0]))
    LED1.value(int(binary[1]))
    LED2.value(int(binary[2]))
    LED4.value(int(binary[3]))
def handler_0(tim0):
    global i 
    count = [1,2,3,4,5,6]
    binarycount(2*count[i])
    i=i+1
    if i == 6:
        i = 0
tim0 = Timer(0)
tim0.init(period=500, mode=Timer.PERIODIC, callback= handler_0)