title: Sass Mixin Modulo not working correctly
body: <p>I want to write a sass mixin that outputs a certain class every 5 steps from 1 to 100. But I can't get the modulo operator to work somehow. No class is created at all.</p>
  
  <p>Here is my code</p>
  
  <pre><code>@mixin flex_percentage($className) {
      @for $i from 1 through 100 {
          @if $i % 5 != 0 {
              .#{$className}#{$i} {
                  width: $i * 1%;    
              }
          }
      }
  }
  @include flex_percentage(p);
  </code></pre>
  
  <p>I also tried <code>$i mod(5)</code> but then it outputs all 100 classes.</p>
  
  <p>I would like to have a output like</p>
  
  <pre><code>.p5 {
      width: 5%;
  }
  .p10 {
      width: 10%;
  }
  .p15 {
      width: 15%;
  }
  </code></pre>