public function process()
    {
        $operands = $this->getOperands();

        if ($operands->containsNull() === true) {
            return null;
        }

        if ($operands->exclusivelySingle() === false) {
            $msg = "The Truncate operator only accepts operands with a single cardinality.";
            throw new OperatorProcessingException($msg, $this, OperatorProcessingException::WRONG_CARDINALITY);
        }

        if ($operands->exclusivelyNumeric() === false) {
            $msg = "The Truncate operator only accepts operands with an integer or float baseType.";
            throw new OperatorProcessingException($msg, $this, OperatorProcessingException::WRONG_BASETYPE);
        }

        $operand = $operands[0];

        if (is_nan($operand->getValue())) {
            return null;
        } elseif (is_infinite($operand->getValue())) {
            return new QtiFloat(INF);
        } else {
            return new QtiInteger(intval($operand->getValue()));
        }
    }