Function for SASS/SCSS to avoid duplicate imports and redundant generated CSS. See http://paul.wellnerbou.de/2015/05/18/avoid-multiple-imports-of-the-same-scss-file-with-sass/ for more details.

import-once-workaround.scss

/* If this function is imported, you can import scss files using:
       
   @if not-imported("your-file") { @import "your-file"; }
*/
$imported-once-files: () !default;

@function not-imported($name) {
  $imported-once-files: $imported-once-files !global;
  $module_index: index($imported-once-files, $name);
  @if (($module_index == null) or ($module_index == false)) {
    $imported-once-files: append($imported-once-files, $name);
    @return true;
  }
  @return false;
}