// if this node has the corresponding rule to be checked,
// push it to the stack.
// if we already have the same rule object, there is no need to
// add it twice.
SElementExp exp = (SElementExp)checks.get(node);
// System.out.println("node tested");
int numRulesAdded = 0;
if(exp!=null ) {
// System.out.println("rule added");
for( int i=0; i<exp.rules.length; i++ ) {