data, and mathematical observations. </span>
<span class="sd">        Color Research &amp; Application, 30(1), 21–30. </span>
<span class="sd">        &lt;https://doi.org/10.1002/col.20070&gt;`_</span>
<span class="sd">    &quot;&quot;&quot;</span>
    
    <span class="k">if</span> <span class="n">KLCH</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
        <span class="n">KLCH</span> <span class="o">=</span> <span class="p">[</span><span class="mi">1</span><span cl