class Screen(object):
    @property    def width(self):
        return self._width

    @width.setter    def width(self,width):
        self._width = width

    @property    def height(self):
        return self._height

    @height.setter    def height(self,height):
        self._height = height

    @property    def resolution(self):
        return self._height*self._width