from machine import Pin
from time import sleep

push = Pin(13, Pin.IN, Pin.PULL_UP)  # declaring GPIO0 as an INPUT pin. 
led = Pin(2, Pin.OUT)               # declaring GPIO2 as an OUTPUT pin.

while True:
# we use if() function to compare the GPIO0 reading state with the LOW state. 
# if the GPIO0 reading is LOW, light ON the LED on GPIO2 with LOW state.
# else means, the GPIO0 reading is HIGH, light OFF the LED on GPIO2 with HIGH state. 
    if push.value() == 0:
        led.value(0) 
        sleep(0.5)
        led.value(1)
        sleep(0.5)