// Adds $value as first index of $list
// -------------------------------------------------------------------------------
// @documentation http://sassylists.com/documentation/#prepend
// -------------------------------------------------------------------------------
// @example prepend(a b c, z)   => z, a, b, c
// @example prepend(a b c, y z) => y z, a, b, c
// -------------------------------------------------------------------------------
// @param $list [List] : list
// @param $value [Literal] : value to prepend to the list
// -------------------------------------------------------------------------------
// @return [List]

@function prepend($list, $value) {
    @if $value and $value != "" and $value != () {
        @return join($value, $list);
    }

    @else {
        @return $list;
    }
}