Drupal: example of hook invoking

invoke_hook.php

<?php
$baz = $qux = t('Arguments');

$bar = array();
foreach (module_implements('foo') as $module) {
  $bar[] = module_invoke($module, 'foo', $baz, $qux);
}

# module_invoke_all('foo', $baz, $qux);

function hook_foo($baz, $qux) {
  return t('It works!');
}