[GitHub] [arrow-datafusion] yjshen removed a comment on pull request #1970: Address typo in ExprVisitable trait documentation

[GitBox <gi...@apache.org>]

yjshen removed a comment on pull request #1970:
URL: https://github.com/apache/arrow-datafusion/pull/1970#issuecomment-1064154488


   ```rust
   struct Print{}
   
   impl ExpressionVisitor for Print {
       fn pre_visit(self, expr: &Expr) -> datafusion_common::Result<Recursion<Self>> where Self: ExpressionVisitor {
           println!("pre {}", expr);
           Ok(Recursion::Continue(self))
       }
   
       fn post_visit(self, expr: &Expr) -> datafusion_common::Result<Self> {
           println!("post {}", expr);
           Ok(self)
       }
   }
   
   #[test]
   fn a() {
       let a = BinaryExpr {
           left: Box::new(Expr::Column(Column::from_name("foo"))),
           op: Operator::Gt,
           right: Box::new(Expr::Column(Column::from_name("bar")))
       };
       a.accept(Print{}).unwrap();
   }
   ```
   and I get
   ```
   pre #foo > #bar
   pre #foo
   post #foo
   pre #bar
   post #bar
   post #foo > #bar
   ```
   
   
   


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