from machine import Pin
import time
led = Pin(12,Pin.OUT)
key = Pin(4,Pin.IN,Pin.PULL_UP)
state = 0
def fun(key):
    time.sleep_ms(5)
    global state  
    if key.value() == 0:
        state = not state
        led.value(state)
key.irq(fun,Pin.IRQ_FALLING)