pub trait PpAnn {
    // Provided methods
    fn pre(&self, _state: &mut State<'_>, _node: AnnNode<'_>) { ... }
    fn post(&self, _state: &mut State<'_>, _node: AnnNode<'_>) { ... }
}pub trait PpAnn {
    // Provided methods
    fn pre(&self, _state: &mut State<'_>, _node: AnnNode<'_>) { ... }
    fn post(&self, _state: &mut State<'_>, _node: AnnNode<'_>) { ... }
}