如何使用 SASS 为页脚创建动态背景图像？

$imgKey: random(5);

$list: "url('http://domain.com/blablabla/apple.png'),
        url('http://domain.com/blablabla/banana.png'),
        url('http://domain.com/blablabla/cherry.png'),
        url('http://domain.com/blablabla/durian.png'),
        url('http://domain.com/blablabla/eggplant.png')";

$nth: nth($list, $imgKey);

#footer-widgets .container .row {
    background-image: $nth;
    background-position: right bottom;
    background-repeat: no-repeat;
}