Drupal 7 variable set up

<?php
/**
 * Implements hook_menu().
 */
function module_menu() {
  $items = array();

  $items['admin/config/site/module'] = array(
    'title' => 'Module configuration',
    'description' => 'Module settings form.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('variable_module_form', 'module'),
    'access arguments' => array('administer site configuration'),
    'type' => MENU_NORMAL_ITEM,
    'file' => 'module.variable.inc',
  );

  return $items;
}


####################

/**
* Implements hook_variable_info().
*/
function module_variable_info($options) {

  $variables['variable_name'] = array(
    'type' => 'string',
    'title' => t('Variable name', array(), $options),
    'description' => t(
      'description', array(), $options),
    'default' => '0',
    'access' => 'administer openbet configuration',
    'required' => TRUE,
    'validate callback' => 'validate_callback',
  );

}

/*
 * Implements hook_variable_settings_form_alter().
 */
function module_variable_settings_form_alter(&$form, &$form_state, $form_id) {
  if (isset($form['#variable_module_form']) && $form['#variable_module_form'] == 'module') {
    $form['#submit'][] = '__callback';
    // ...
  }
}