title: How to make LESS combine CSS rules with a comma
body: <p>For example:</p>
  
  <pre><code>.icon-pinterest{
      color:#CC2027;
      background: #fff;
      &amp;:hover{
          color:#CC2027;
          background: #fff;
      }
  }
  </code></pre>
  
  <p>This will generate:</p>
  
  <pre><code>.icon-pinterest {
    color: #cc2027;
    background: #fff;
  }
  
  .icon-pinterest:hover {
    color: #cc2027;
    background: #fff;
  }
  </code></pre>
  
  <p>But I want it as the following:</p>
  
  <pre><code>.icon-pinterest,
  .icon-pinterest:hover {
    color: #cc2027;
    background: #fff;
  }
  </code></pre>
  
  <p>I think maybe I can use the extend expression?</p>