public IRuleNode visit(External obj, Object arg) throws RIFException {
final Conjunction conjunction = new Conjunction();
conjunction.setParent((IRuleNode) arg);
RuleVariable alias = new RuleVariable(aliasString + aliasCtr++);
conjunction.addExpr(alias);
Equality comp = new Equality();
comp.leftExpr = new RuleVariable(alias.getName());
comp.leftExpr.setParent(comp);
comp.rightExpr = obj;