Implements hook_node_access().
function node_access_test_node_access($node, $op, $account, $langcode) {
$secret_catalan = Drupal::state()
->get('node_access_test_secret_catalan') ?: 0;
if ($secret_catalan && $langcode == 'ca') {
// Make all Catalan content secret.
return NODE_ACCESS_DENY;
}
return NODE_ACCESS_IGNORE;
}