buildElement() {
    const templateString = fs.readFileSync(this.__template, {encoding: 'utf-8'});
    const parser = new DOMParser();
    const doc = parser.parseFromString(templateString, 'text/html');
    return doc.querySelector('.pio-template-root').cloneNode(true);
  }
Creates an HTML element for a view.

Subclasses must either provide a __template attribute (e.g., via
@withTemplate decorator) or override this method.