if (arg instanceof AttributeExprEx) {
AttributeExprEx variable = (AttributeExprEx) arg;
NodeMaker nm = variable.getNodeMaker();
DetermineNodeType filter = new DetermineNodeType();
nm.describeSelf(filter);
if (!filter.isLimittedToLiterals()) {
// type error, return false?
logger.warn("type error: " + variable + " is not a literal, returning FALSE");
expression.push(Expression.FALSE);
return;