title: concatenate strings using sass
body: <p>I would like to write a sass loop like so.</p>
  
  <pre><code>fractions: '';
  @for $i from 1 through 4 {
      $fractions : $fractions + 1fr + '';
      .grid-#{$i} {
          grid-template-columns: fractions;
          display: block;
      }
  }
  </code></pre>
  
  <p>I would like the output to be something like,</p>
  
  <pre><code>.grid-1 {
      grid-template-columns: 1fr; 
  }
  .grid-4 {
      grid-template-columns: 1fr 1fr 1fr 1fr; 
  }
  </code></pre>
  
  <p>not </p>
  
  <pre><code>.grid-1 {
      grid-template-columns: " 1fr"; 
  }
  .grid-4 {
      grid-template-columns: " 1fr 1fr 1fr 1fr"; 
  }
  </code></pre>
  
  <p>I'm looking for a sass utility/function that I can use to remove the quote around the strings.</p>