Compass中的flexbox参数问题

Question

我在以下代码中获得了Mixin flexbox doesn't have an argument named $version。我安装了Compass 1.0.1。

@import "compass/css3/flexbox";

@mixin all-spec-display-flex() {
    @include flexbox((display: box, flex-direction: row), $version: 1);
    @include flexbox((display: flexbox, flex-direction: row), $version: 2);
    @include flexbox((display: box, flex-direction: row));
}

我在Compass中打开了_flexbox.scss文件，我确实在那里看到了$version param。