GUMP::validate_doesnt_contain_list PHP Method

    protected function validate_doesnt_contain_list($field, $input, $param = null)
    {
        $param = trim(strtolower($param));
        $value = trim(strtolower($input[$field]));
        $param = explode(';', $param);
        if (!in_array($value, $param)) {
            // valid, return nothing
            return;
        } else {
            return array('field' => $field, 'value' => $value, 'rule' => __FUNCTION__, 'param' => $param);
        }
    }