So, i have a LED controlled by a Raspy, and also a basic GUI with just a push button, I want it to behave as follows:

* LED blinks when the push button IS NOT pressed.
* LED should stay ON continually when the push button IS pressed.

When I execute light starts blinking, but **the button does not show up.**
When I interrupt the program, the button shows up. Why?

```
from tkinter import *
import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BOARD)
GPIO.setup(8, GPIO.OUT)
GPIO.output(8, False)
buttonPressed = False

master = Tk()

def callback():
    GPIO.output(8, True)
    buttonPressed = True

w = Button(master, text="Turn on light", command = callback)
w.pack()

while True:
    if buttonPressed == False:
        GPIO.output(8, True)
        time.sleep(0.5)
        GPIO.output(8, False)
        time.sleep(0.5)
    else:
        GPIO.output(8, True)

```