public function _valid_idiom($str)
{
$lang_files = list_lang_files($str);
if (empty($lang_files['admin']) and empty($lang_files['main']) and empty($lang_files['module'])) {
$this->form_validation->set_message('_valid_idiom', $this->lang->line('error_invalid_idiom'));
return FALSE;
} else {
// else validation is not successful
return TRUE;
}
}