drupalcampbristol/vendor/chi-teck/drupal-code-generator/templates/d7/hook/validate.twig

/**
 * Implements hook_validate().
 */
function {{ machine_name }}_validate($node, $form, &$form_state) {
  if (isset($node->end) && isset($node->start)) {
    if ($node->start > $node->end) {
      form_set_error('time', t('An event may not end before it starts.'));
    }
  }
}