{"ast_node_type":"variable","tokens":[{"end":99,"kind":"keyword","start":0,"text":"let"}]}
            let halfladder = self.drop_halfladder(&unwind_ladder, &dropline_ladder, succ, &fields);
        let dropline_ladder: Vec<_> = if let Some(succ) = dropline {
            halfladder.into_iter().map(Some).collect()