create(display) {
    if (this.options && (this.options.flatten || this.options.renderMode === 'flat')) {
      display = 'form';
    }
    this.display = display;
    if (Displays.displays[display]) {
      return new Displays.displays[display](this.element, this.options);
    }
    else {
      // eslint-disable-next-line new-cap
      return new Displays.displays['webform'](this.element, this.options);
    }
  }
Create a new form instance provided the display of the form.
@param {string} display - The display of the form, either "wizard", "form", or "pdf"
@returns {Webform|Wizard|PDF} - The new form instance for the display.