class Screen(object):   def __init__(self, width, height):      self._width = width      self._height = height   @property   def width(self):      return self._width   @property   def height(self):      return self._height   @property   def resolution(self):      return self._width * self._height   @width.setter   def width(self, width):      self._width = width   @height.setter   def height(self, height):      self._height = height