public function getAllTxrefs()
    {
        $allTxrefs = array();
        if (is_array($this->txrefs)) {
            $allTxrefs = array_merge($allTxrefs, $this->txrefs);
        }
        if (is_array($this->unconfirmed_txrefs)) {
            $allTxrefs = array_merge($allTxrefs, $this->unconfirmed_txrefs);
        }

        if (count($allTxrefs) == 0)
            return null;
        else
            return $allTxrefs;
    }