docs: private static AbstractPlanNode handleOrderBy(AbstractParsedStmt parsedStmt, AbstractPlanNode root) {
          assert (parsedStmt instanceof ParsedSelectStmt || parsedStmt instanceof ParsedUnionStmt ||
                  parsedStmt instanceof ParsedDeleteStmt);
  
          if (! isOrderByNodeRequired(parsedStmt, root)) {
              return root;
          }
  
          OrderByPlanNode orderByNode = buildOrderByPlanNode(parsedStmt.orderByColumns());
          orderByNode.addAndLinkChild(root);
          return orderByNode;
      }