public function substractValue($values)
    {
        if (isset($values[$this->id]) && ! Cuztom::isEmpty($values[$this->id])) {
            if (is_array($values[$this->id])) {
                $value = isset($values[$this->id][0]) ? maybe_unserialize($values[$this->id][0]) : null;
            } else {
                $value = maybe_unserialize($values[$this->id]);
            }
        } else {
            $value = $this->default_value;
        }

        return apply_filters('cuztom_field_value', $value, $this);
    }