import time, random
from gpiozero import LED, Button

led1 = LED(23)
# test
led1.on()
time.sleep(2)
led1.off()

button1 = Button(25)
end = "Y"
best = 100
print("press buttonn when LED is on")
while end =="Y":
    time.sleep(random.randint(1,5))
    start = time.time()
    led1.on()
    button1.wait_for_press()
    button1.when_pressed = led1.off()
    stop = time.time()
    duration = stop-start
    print("reaction time in s",duration)
    if duration<best:
        best = duration
        print("You got a lowscore!")
    end = input("Again [Y]es/[N]o ")#I've got no second button