@function unite($list, $glue: ', ') {
  @if length($list) == 1 {
    @return $list;
  } @else {
    $string: '';
    @each $item in $list {
      @if $string != '' {
        $string: $string + $glue;
      }
      $string: $string + $item;
    }

    @return $string;
  }
}