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

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

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

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

        $operand = $operands[0];

        return new QtiFloat(floatval($operand->getValue()));
    }