internal override void Walk(NodeWalker walker, int depth, bool wrap)
 {
     walker("(", TestValue ? TrueValue : FalseValue, depth);
     Condition.Walk(walker, depth + 1, false);
     walker(" ? ");
     TrueNode.Walk(walker, depth + 1, false);
     walker(" : ");
     FalseNode.Walk(walker, depth + 1, false);
     walker(")");
 }