protected function addToDataPool($key, $value, $step = Doozr_Form_Service_Constant::DEFAULT_STEP_FIRST)
    {
        // Get storage ...
        $pool = $this->getDataPool();

        $pool[Doozr_Form_Service_Constant::IDENTIFIER_DATA][$step][$key] = $value;

        $this->setDataPool($pool);

        return true;
    }