sass vs less

quantity-query.less

.quanty-query(@number, @comparison, @content) when (@comparison = 'greater'), (@comparison = 'more'), (@comparison = '>'){
  &:nth-last-child(n @{number}):first-child {
    &,
    & ~ * {
      @content();
    }
  }
}
.quanty-query(@number, @comparison, @content) when (@comparison = 'fewer'), (@comparison = 'less'), (@comparison = '<'){
  &:nth-last-child(-n @{number}):first-child {
    &,
    & ~ * {
      @content();
    }
  }
}
.quanty-query(@number, @comparison, @content) when (default()){
  &:nth-last-child(@{number}):first-child {
    &,
    & ~ * {
      @content();
    }
  }
}

quantity-query.scss

@mixin quantity-query( $number, $comparison: 'equal' ) {
    @if index( ('greater' 'more' '>'), $comparison ) {
        $nth: 'n + #{$number}';
      } @else if index( ('less' 'fewer' '<'), $comparison ) {
        $nth: '-n + #{$number}';
      } @else if index( ('equal' 'same' '='), $comparison ) {
        $nth: $number;
      } @else {
        @warn "Sorry, that’s an invalid $comparison value."
      }
      
    &:nth-last-child(#{$nth}):first-child {
        &,
        & ~ * {
          @content;
        }
      }
}