xmlsitemap_node_form_alter wrong php syntax

This is wrong

function xmlsitemap_node_form_alter(array &$form, array &$form_state, $form_id) {

right code here

function xmlsitemap_node_form_alter(array &$form, array $form_state, $form_id) {

also documentation on api.drupal.org is wrong about hook_form_alter