public virtual void PostWalk(IfStatement node)
 {
 }
 // IfStatement
 public virtual bool Walk(IfStatement node)
 {
     return(true);
 }
 public override void PostWalk(IfStatement node)
 {
 }
 // IfStatement
 public override bool Walk(IfStatement node)
 {
     return(Contains(node));
 }
 // IfStatement
 public override bool Walk(IfStatement node)
 {
     return(false);
 }