public function getStoredData($source = null)
    {
        if (null === $source) {
            $result = $this->store;

        } else {
            if (false === isset($this->store[$source])) {
                throw new Doozr_Base_Presenter_Exception(
                    sprintf('No stored data for source (key) "%s"', $source)
                );
            }

            $result = $this->store[$source];
        }

        return $result;
    }