er"</span> {</span>
    <span class="hljs-at_rule">@<span class="hljs-keyword">warn</span> <span class="hljs-string">"base-value: #{$base-value} is not a number"</span>;</span>
    <span class="hljs-at_rule">@return<span class="hljs-preprocessor"> null</span>;</span>
  }
  $max<span class="hljs-value">: length($values);</span>
  <span class="hljs-at_rule">@<span class="hljs-keyword">if</span> $max ==<span class="hljs-preprocessor"> 1</span> {</span> <span class="hljs-at_rule">@return<span class="hljs-prepro