Weird Loop Behaviour

[Yigit Turgut]

Hi,

In the following code, I am trying to run "black" screen for 3 seconds
and respectively 2 seconds "white" screen. Black routine takes 3
seconds and white 2 seconds, 2 x black + white = 8 seconds which
should be the expected value but when I run it I get black-white-black-
white   instead of black-white-black. Couldn't figure out what is
wrong thus sharing the code as well ;

white = False
     while(end<8.00):
      end = time.time() - start
      if white:
       screen.fill((255, 255, 255))
	time.sleep(2)
      else:
      	screen.fill((0, 0, 0))
	time.sleep(3)
      white = not white
      pygame.display.update()
     pygame.quit()