How to use the @smile-io/ember-polaris/helpers/polaris-select/is-group.isGroup function in @smile-io/ember-polaris

options.forEach((optionOrGroup) => {
    if (isGroup(optionOrGroup)) {
      flatOptions = flatOptions.concat(optionOrGroup.options);
    } else {
      flatOptions.push(optionOrGroup);
    }
  });

function normalizeOption(option) {
  if (isString(option)) {
    return normalizeStringOption(option);
  } else if (isGroup(option)) {
    let { title, options } = option;
    return {
      title,
      options: options.map((option) => {
        return isString(option) ? normalizeStringOption(option) : option;
      }),
    };
  }

  return option;
}