import machine
import utime
import urandom

led=machine.Pin(15,machine.Pin.OUT)
button=machine.Pin(14,machine.Pin.IN)

def button_press(pin):
    button.irq(handler=None)
    rection_time=utime.ticks_diff(utime.ticks_ms(),timer_light_off)
    print("your reaction time was "+str(rection_time)+ "milliseconds!")

led.value(1)
utime.sleep(urandom.uniform(5,10))
led.value(0)
timer_light_off =utime.ticks_ms()
button.irq(trigger=machine.Pin.IRQ_RISING,handler=button_press)