Get largest value from a map in Sass using max()

_max.scss

// Sass 3.3
// This function can be used to get the largest number from a nested map. Currently only supports 1 sub-map.

// Uses max() to get the biggest number in a map
// See max() docs for reference: http://sass-lang.com/documentation/Sass/Script/Functions.html#max-instance_method
@function get-max($map, $key) {
    $list: ();

    // Loop through each item in the map
    @each $map-key, $sub-map in $map {
        // Add the desired value to our list, from the sub-map
        $list: append($list, map-get($sub-map, $key), comma);
    }

    // Get the largest number from our list
    @return max($list...);
}

$example: (
    foo: (
        height: 190px,
        width: 200px
    ),
    bar: (
        height: 240px,
        width: 100px
    ),
    foobar: (
        height: 230px,
        width: 300px
    )
);

$tallest: get-max($example, height); // Returns 240px
$widest: get-max($example, width); // Returns 300px