Pinq\Queries\Builders\ExpressionInterpreter::getOptionalArgumentAt PHP Method

    protected final function getOptionalArgumentAt($index, O\MethodCallExpression $methodExpression)
    {
        $argumentExpressions = $methodExpression->getArguments();
        if (isset($argumentExpressions[$index])) {
            if ($argumentExpressions[$index]->isUnpacked()) {
                throw new PinqException('Cannot get argument from method call %s at index %d: argument unpacking is not supported', $methodExpression->getName()->compileDebug(), $index);
            }
            return $argumentExpressions[$index]->getValue();
        } else {
            return null;
        }
    }