def setUp():
   global window
   window = Display("Visualizer", getScreenWidth(), getScreenHeight())
   gradient = Rectangle(0, 0, getScreenWidth(), getScreenHeight(), Color.BLACK, True, 1)
   window.add(gradient)
   updateColor(gradient)


#input: None
#return: the width of the screen
def getScreenWidth():
  return Toolkit.getDefaultToolkit().getScreenSize().width

#input: none
#return: the height of the screen
def getScreenHeight():
  return Toolkit.getDefaultToolkit().getScreenSize().height