{"ast_node_type":"variable","tokens":[{"end":87,"kind":"keyword","start":0,"text":"let"}]}
            let FormatArgsPiece::Placeholder(placeholder) = piece else { return None };
        let elements = ctx.arena.alloc_from_iter(fmt.template.iter().filter_map(|piece| {
            Some(make_format_spec(ctx, macsp, placeholder, &mut argmap))