from machine import Pin
from time import sleep

led = Pin(10, Pin.OUT)
sw = Pin(21, Pin.IN, Pin.PULL_UP)

while True:
  if sw.value() == 0:
    led.value(1)
    print(led.value())
    sleep(0.25)
  else:
    led.value(0)
    print(led.value())
    sleep(0.25)