public function getNextToken()
    {
        if (null === $this->_nextToken) {
            $tokenSelect = $this->tracker->getTokenSelect();
            $tokenSelect
                    ->andReceptionCodes()
                    ->forPreviousTokenId($this->_tokenId);

            if ($tokenData = $tokenSelect->fetchRow()) {
                $this->_nextToken = $this->tracker->getToken($tokenData);
                $this->_nextToken->_previousToken = $this;
            } else {
                $this->_nextToken = false;
            }
        }

        return $this->_nextToken;
    }