{"ast_node_type":"variable","tokens":[{"end":20,"kind":"keyword","start":0,"text":"let"}]}
            let br =
                Ty::new_imm_ref(tcx, ty::Region::new_bound(tcx, ty::INNERMOST, br), param(0));
                ty::BoundRegion { var: ty::BoundVar::from_u32(1), kind: ty::BoundRegionKind::Anon };