public function ajaxLeadershipCallback(array $form, FormStateInterface $form_state) {
    $triggering_element = $form_state->getTriggeringElement();
    if ($triggering_element['#name'] == 'previous') {
      $form_state->set('page', $form_state->get('page') - 1);
    }
    elseif ($triggering_element['#name'] == 'next') {
      $form_state->set('page', $form_state->get('page') + 1);
    }
    else {
      $form_state->set('page', 0);
    }
    $new_form = $this->formBuilder->rebuildForm($this->getFormId(), $form_state, $form);
    return $new_form;
  }