          </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1" id="description">
        <h2>Description</h2>
        <p>
            <code class="function">mix</code> performs a linear interpolation between <em class="parameter"><code>x</code></em>
            and <em class="parameter"><code>y</code></em> using <em class="parameter"><code>a</code></em> to weight between them. The return value
            is computed as follows:
            <math overflow="scroll">
