> <span class="Other">=</span> <span class="Keyword">ref</span> <span class="Keyword">object</span>
  <span class="Keyword">case</span> <span class="Identifier">isString</span><span class="Operator">*</span><span class="Other">:</span> <span class="Identifier">bool</span>
  <span class="Keyword">of</span> <span class="Identifier">true</span><span class="Other">:</span>
      <span class="Identifier">str</span><span class="Operator">*</span><span class="Other">:</span> <span class="Identifier">string</span>
