@mixin add-aspect($ratio…) {

$ratio: unpack($ratio);
$important: null;
@if has-important($ratio) {
  $ratio: nth($ratio, 1);
  $important: "!important";
}

@if map-has-key($project-aspect-ratios, $ratio) {
  box-sizing: border-box #{$important};
  height: 0 #{$important};
  overflow: hidden #{$important};
  padding: 0 0 map-get($project-aspect-ratios, $ratio) #{$important};
} @else {
  @error '`#{$ratio}` is not a valid key in $project-aspect-ratios. Valid values: #{map-keys($project-aspect-ratios)}';
}

}