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

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

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

        if ($operands->exclusivelyPoint() === false) {
            $msg = "The Inside operator only accepts operands with a baseType of point.";
            throw new OperatorProcessingException($msg, $this, OperatorProcessingException::WRONG_BASETYPE);
        }

        $operand = $operands[0];
        $coords = $this->getExpression()->getCoords();

        return new QtiBoolean($coords->inside($operand));
    }