from machine import Pin
import time

led_pin = Pin(2, Pin.OUT)
button_pin = Pin(4, Pin.IN, Pin.PULL_UP)

def toggle_led(pin):
    led_pin.value(not led_pin.value())

button_pin.irq(trigger=Pin.IRQ_FALLING, handler=toggle_led)

while True:
    time.sleep_ms(100)