/**
  * Accepts the Visitor for leave behavior.
  *
  * @param visitor
  */
 public void leave(IRVisitor visitor) {
   visitor.leave(this);
 }
 /**
  * Accepts the Visitor for enter behavior.
  *
  * @param visitor
  * @return boolean
  */
 public boolean enter(IRVisitor visitor) {
   return (visitor.enter(this));
 }