Function structural_visit 

pub fn structural_visit<R, M>(
    root: &R,
    visitor: impl IntoVisitor<M>,
) -> Result<Option<VisitInterrupt>>
where
    for<'x> AnyView<'x>: From<&'x R>,

Visit root with a StructuralVisitor or typed callback chain.

A matching callback owns recursion; unmatched values use default child traversal. Use VisitCallbacks to attach mutable state to the chain.