Visitor pattern implementation for Babel AST.

Example

```rust // Visit all Identifier nodes in the Babel AST and change the optional field to // Some(true) for each of them.

use swcbabelvisit::{VisitMut, VisitMutWith}; use swcbabelast::{Identifier, File};

struct Visitor;

impl VisitMut for Visitor { fn visitmutidentifier(&mut self, node: &mut Identifier) { node.optional = Some(true); } }

let ast: File = getbabelast(); let mut v = Visitor {}; ast.visitmutwith(&mut v); ```