Method f_up

datafusion/expr/src/logical_plan/plan.rs:4676–4688

(&mut self, plan: &'n LogicalPlan)

        }

        fn f_up(&mut self, plan: &'n LogicalPlan) -> Result<TreeNodeRecursion> {
            let s = match plan {
                LogicalPlan::Projection { .. } => "post_visit Projection",
                LogicalPlan::Filter { .. } => "post_visit Filter",
                LogicalPlan::TableScan { .. } => "post_visit TableScan",
                _ => {
                    return not_impl_err!("unknown plan type");
                }
            };

            self.strings.push(s.into());
            Ok(TreeNodeRecursion::Continue)
        }
    }

    #[test]