lass="idl"><a data-link-type="idl" href="#customstateset" id="ref-for-customstateset①">CustomStateSet</a></code>
 interface had no <code class="idl"><a data-link-type="idl" href="#dom-customstateset-add" id="ref-for-dom-customstateset-add①">add(value)</a></code> operation, with
 <var>value</var> arguemnt.</p>
   </ol>
   <div class="example" id="ex-non-boolean-state">
    <a class="self-link" href="#ex-non-boolean-state"></a>
<a data-link-type="dfn" href="#states-set" id="ref-for-states-set①">States s