protected virtual Expression VisitSet(SetExpression node)
 {
     VisitBinaryBranch(node.Left, node.NodeType);
     Append(ToSign(node.NodeType));
     VisitBinaryBranch(node.Right, node.NodeType);
     return(node);
 }
 protected virtual Expression VisitSet(SetExpression node)
 {
     VisitBinaryBranch(node.Left, node.NodeType);
     Append(ToSign(node.NodeType));
     VisitBinaryBranch(node.Right, node.NodeType);
     return node;
 }