ror(`Invalid serializable ${serializable}`);
    }
    const delegatesAttr = delegatesFocus ? ' shadowrootdelegatesfocus=""' : '';
    const serializableAttr = expectedSerializable ? ' shadowrootserializable=""' : '';
    const clonableAttr = clonable ? ' shadowrootclonable=""' : '';

    if (allowsShadowDom && declarativeShadowDom) {
      const html = `<${elementType}>${lightDOMContent}<template ` +
          `shadowrootmode=${mode}${delegatesAttr}${serializableAttr}` +
          `${clonableAttr}>`;
     